Feeling very good-zone-y right now. Just had my first session of a new campaign. I came up with a much more open-ended adventure idea, did a ton of setting work beforehand so that many good skill checks are there in place (frex, I know what Gather Information DC will get the PCs what level of information, and I've got multiple information levels). It's a d20 Modern murder mystery (part of an action thriller campaign), and people seemed to really enjoy it.
Best part (since multiple people are doing modern) was the combat. 2 (well, 3, but one was not involved at all) 6th-level PCs against 4 Tgh1/Fst1 college students. The PCs were FBI-like investigators, although much less respected (a law enforcement arm of the Bureau of Indian Affairs), and the college students were angry that the PCs were trying to stop them from cleaning out their dead friend's apartment, since they'd already answered questions. It ended up as a melee fight... in a 5' wide hallway.
I used the D&D 3.5 rules for fighting in a cramped space, and it was just AWESOME. The PCs, all of whom had guns, were trying to do the right thing by not shooting the college kids, and the college kids were throwing tons of ineffectual punches. People were lined up shoulder-to-shoulder, everyone was awkward and off-balance -- at one point, one square had three people in it -- two college kids, and the prone PC who'd tried to break through their lines with an Overrun and gotten tripped for his trouble. Due to PC conflict, the fight ended with one PC grappling another PC and hollering for him to calm the heck down (he'd just done lethal damage with CMA to one of them, in the form of a nasty uppercut), while the college kids, who had delivered all of 8 points of nonlethal damage across 3 hits, ran off and called the cops.
Awkward, non-cinematic, and completely the way a real-life fight involving lots of people in a narrow hallway should go. After a long time of "open door, see something hostile to me, kill it", the idea of NOT drawing their handguns was a breath of fresh air. I'm going to make sure that they get something to shoot, so that they don't feel unhappy about taking those gun feats, but it was a great way to start the campaign.