Wow, this post became a lot longer than I was intending.
I've had satisfying endings to three campaigns, each of which lasted between a year and a year and a half, though we played weekly and I seem to recall you guys only meet about once a month.
I'm a writer, so what was natural for me was to write an epilogue. This is how we ended the second of my 'satisfying-ending' campaigns. After the last session, in which they had defeated the last villain and had achieved their goals (or had been thwarted satisfactorily), I asked the players where they thought their characters would go, what they would do, and I wrote a 15-page story to convey it all. They all liked it, except for the one player who didn't get back t me for over a week, and when she did she told me three things not to do:
1. Don't kill my character.
2. Don't kill my tribe.
3. Don't let the secret my tribe was keeping get out.
Well, I got 0 for 3 on that one. The rest of the players loved it, because they saw poetic justice for a power-gamer who never told the party anything about herself, and who refused to get her large force of allies involved in helping the party's goals. They wanted to know what was up with her, so I satisfied 80% of my group.
The third of the 'satisfactory-ending' campaigns was my recent modern fantasy campaign, called The Long Road. We'd had an epic battle with weird postmodern stuff like killing vampire King Arthur in the Dungeon of Avalon with the aid of a Power Point presentation while Michael Jackson waited by the sidelines to be healed so they could save the world. I didn't think I could really top that, so for the last session I just told the group we would discuss what to do, roleplay some resolution to various personal rivalries, and let them decide how to end it.
They had one last favor they owed a friend, so after ensuring the world was saved (and mocking the 'heroic good guy organization' about how they had been useless while the PCs were awesome), they went for one final fight against a Juiblex-esque demon shogun in fey Japan. We had a car chase while being pursued by demon samurai, a haiku puzzle, and a diceless battle against the shogun in which the party used all the tricks they had joked about but never tried because it would be impossible to succeed the necessary checks. I believe they threw a BMW with a nuke in the trunk at it, then teleported it to the moon, where it exploded. One of the PCs was supposedly killed in the process, which was sort of deserved because he had been a bastard who never quite managed to repent. He was wanted for murder, and if he had survived he would just have been arrested anyway. Better to go out a hero.
We ran through the denoument, with the 'good guy organization' filling the survivors in on all the secrets they had missed, and promising to track down all the loose ends and tie them up. The group managed to leak the existence of magic to the general world, which they had wanted to do all along, and a slow but safe change was occuring, thanks in no small part to the renewed vigor and career of Michael Jackson. One PC managed to get a politician he hated forced out of office, another one was reunited with a lover, and a duo who kinda didn't like each other hit the road to find more adventure, both grudgingly admitting they counted the other as a friend.
The final scene was those two driving away down Interstate 10. The camera stayed in place, though, watching them go for a few moments before panning to reveal a figure stepping out of the woods, looking a bit bedraggled. He holds out a thumb, and a moment later a car pulls over.
The driver rolls down his window and asks if the man where he's headed. Only then do we turn to reveal the PC who was believed dead in the fight against the demon shogun. He considers the driver's question, shrugs, smiles charmingly, and says one place is as good as any other. He gets in, the car drives off, and we fade to black.
It was a good ending, though we had to slightly change gears from our normal gaming style, so that we could discuss possibilities and decide on the best one, instead of having to go back and forth making stuff up as we went along.
Then there was my favorite. In the first of the 'satisfactory-ending' campaigns, we were building to a tragedy. The party was in the middle of a large conflict between the good guys and the bad guys, and they were working toward their own agenda rather than joining either side. One of the PCs had turned to evil (but it was totally appropriate), and his player left the game because he was graduating college and needed to prep for finals. Another had switched sides to join the good guys right as her player was graduating, which dropped the group from 5 players to 3.
In the third to last session, the remaining characters planned a last ditch effort against their enemy (who was the main bad guy, but they wanted to defeat her for personal reasons), but the plan went awry, and they were ambushed. One PC -- a weretiger named Stalen -- fought to the death to let the others escape, leaving only two. One of these two -- Rhuarc -- needed vengeance, and the other -- Malek -- was just Rhuarc's friend, and loyal to the end despite the odds.
The villains were evil drow-type elf shadow mages and assassins, and Rhuarc had been training with one of their agents, unknowingly serving their goals. True, he had gained a cool poison bite ability for assassinations, and other drow-ish powers, but he valued his freedom over power, and would fight anyone who tried to take it from him.
For the second to last session, Stalen's player took time off, figuring he was out of the game. However, in a bizarre surprise, one of the players who had left the game over a year earlier for his graduation was back in town, and so his errant knight Stanley returned to the last two PCs and told them of where he had been and the knowledge he had learned on his quest. He pledged to aid them, for the unborn child of his god was trapped by the main villain. They assaulted the villain's compound and after an epic five-hour battle which saw the defeat of a long-term foe thanks to a truly great bit of teamwork, they released the trapped godling, which vanished. However, the enemy forces were too overwhelming, and they were captured.
Before the last session, I talked to Stalen's player, and got his OK for a plan, and told him to show up to the game.
The last session started with the PCs being brought like guests before the main villain. To really get what happened you'd have to understand the whole backstory, but ultimately the villain was revealed to be Rhuarc's mother, suspected dead but in truth possessed by a succubus she had made a pact with in order to get revenge for the murder of her husband years earlier. They had thought it was her, but hadn't realized the demon aspect, which made a lot of the events of the campaign tie together in a massive revelation. Plus, when they realized that most of the minions they had been killing had been demon-spawned offspring of Rhuarc's mother, it kinda creeped them out.
The demon had set up a whole tangled web of deceits, and was poised to drop the world into chaos and doom. If she died, by the terms of the agreement, Rhuarc's soul would be condemned to the abyss. Now, I had provided Rhuarc's player an out, so he could banish the demon without killing his mother or dooming himself, but that choice required him to spare someone else who he really wanted revenge on, a knight named Marinus who had helped kill his father.
The succubus had, of course, made sure Marinus was present.
She gave Rhuarc the option: Take revenge on Marinus and kill me as well, saving the world but dooming yourself, or spare Marinus, save your soul, and doom the world.
It was a demon's choice, but I didn't want to end on a down note, so as the roleplaying was about to reach a climax, Stalen (whose body had been retrieved for reanimation and stored nearby in the villain's complex) appeared, revived and empowered by bonding with the rescued godling. The weretiger tore into the room and killed a few guards, which provided weapons for the other PCs. Malek, a classical thief, slipped from his manacles and freed Rhuarc and Stanley. Stanley grabbed a sword and began to fight his way toward Marinus, knowing the man could potentially expel the demon if he was freed.
Rhuarc grabbed a sword, considered his options, and killed Marinus.
With a high tumble check Rhuarc leapt through the throng of guards and chased after his mother as she fled to her ritual chamber, leaving the others behind to deal with the minions. He pursued her through the shadowed tunnels of the compound, and found her hastily trying to complete her ritual. Around this time I stopped running the combat with the other PCs, even though it was not clear who the victor would be. I decided to focus on Rhuarc. They were alone, and would not be disturbed.
The battle between mother and son lasted a few rounds, but eventually she succeeded in paralyzing him with a hold spell. A perverse being, the demon wearing his mother's flesh approached to embrace him and drain the life from him in a kiss, simultaneously poisoning herself with the venom in his mouth. After a few rounds, her mortal heart began to stop. She staggered away and fell to the ground, and Rhuarc shook free of the hold spell.
He raised his sword for the killing blow, and the demon looked up with a dying smile, saying, "The murder of thousands pales to the pleasure of making one man destroy himself."
Rhuarc killed her, and that's where we ended the game.