I agree with SDD, ToT and BTMRR. I like PeopleMover after dark as well. Basically any of the roller coasters or rides that go high so you can see the lights. Heck, I even enjoy doing the Swiss Family Treehouse after dark and if you can be at the higher points during FWs it's a pretty good view.
I'll add Main Street in MK is pretty when all lit up at night and the main drag at HS and street ToT is on. A lot of people like Pandora in AK at night, it doesn't do much for me but each his own. All the parks have an icon that does a show at night and all are pretty cool, I really like the ToT and Tree of Life ones. I think they are bringing back the lighted sidewalks at Epcot but know when.