I can see LG. Necromancers who focus on putting down the dead instead of raising and assassins who only target evil targets that are causing evil. A LG assassin might even be working for a holy order or a government-backed guild.
And, paladins can be evil. The Oath of Vengeance seems particularly suited to the evil alignments.
I can imagine a necromancer who helps people say farewell to their deceased loved ones, by bringing them back one last time. Or who helps a farmer who just lost his son, by animating the dead to help him with his hard labor. A necromancer could help people when the dead are not at peace, and to figure out what is amiss in the realm of the dead. A necromancer might also be able to discover the truth behind a murder, by simply asking the victim.
Assassins could be merciful. The act of taking a life is obviously not always a bad thing, and does it really matter if you use poisons, or attack from the shadows, or in a fair fight? Its dubious to slap different moral spectrums on actions that basically have the same outcome. An assassin might be the only way to rid a country of its cruel despot, who would otherwise be untouchable.
As for paladins, I think any sufficiently lawful good character could become a fanatic. And a fanatic who is lawful good, might as well be lawful evil, if looked at from a different angle. Paladins can also become corrupted, or they can fall from their faith.
I've decided to add some concrete examples from my session last night to make sure my stance on the matter is clear:
Encounter A: the PCs (a necromancer and an assassin) surprise 4 cult fanatics sitting around a table eating a meal in their shared room. No need for minis because the environment is simple, the positioning isn't going to matter beyond is/isn't near the table, and the fanatics might not even be getting to take actions (as evident by the way it played out: one fanatic killed on the assassin's first turn, the rest stuck in a web spell, then another fanatic dead on the assassin's second turn, and one wounded by the necromancer, then the fanatics cast some spells trying to paralyze the assassin and damage the necromancer to break concentration, and died within the next two rounds for failing to do either).
Encounter B: the necromancer, two zombies under her control, and the assassin are in the cult's temple, when they realize a giant constrictor is hiding inside a bell near the center of the room, and it slithering out sounds the bell, which is answered by 3 of the four entrance to the temple opening and enemies coming forth; the cult leader from one, 20 skeletons from another, and 20 zombies from the last - so out come the dungeon tiles to show the room and its furnishings and a detailed position for each of the 46 combatants. The great benefits were knowing how quickly each party member got surrounded, and how many of those zombies were in the area of the lightning bolt spell the assassin cast from a ring of spell storing. In the end, the battle was memorable for the players, but the necromancer player is lamenting not having chosen any area effect spells as of yet (but she is 34 experience from reaching 7th level, so I expect she'll be remedying that very soon).
This is how I tend to handle it as well. If the battle situation is easy to describe, then there's no need for miniatures. A simple bar fight for example, relies very little on precise details. The players might flip a table, or throw a chair. But exact distances, measurements and cover, are not really relevant.
But when there's a big battle, with height differences, cover, difficult terrain, and magic, then I bring out the miniatures. Specifically when the players are engaged in ranged combat, and are taking cover, or when AOE spells are being used, then it becomes important to me to illustrate the battle. And if no miniatures are available, simple plastic pawns will suffice.
