In short, all of MK!
The whole park just has a magical feel after dark.
Among my top five: Haunted Mansion!, PotC, BTMRR, Splash, Aladdin/AstroOrbiter. Another ride we always do at night is IaSW. not because the ride is any different, but because the lines are SO much shorter. I always chuckle- daytime waits are long whereas night waits are often nothing.
At Epcot, the Wrold Showcase is where I feel the difference. I suppose TT, is a little different at night, but the lighting in the WS makes it feel special. Especially if the weather is nice, and you can eat outside.
In DTD, eating outside is a plus. I think my favorite is now gone (enclosed). It was the QS Wolfgang Puck's.
Mostly AK is closed at night, but the Yeti ride after dark was kind of neat. I'm pretty sure when it is open past dark the animal attractions are all closed. Incidentally, they also all close during a thunderstorm.
For us, HS is a half day park. If we are there after dark it is to take advantage of shorter lines. One thing that I suppose stands out a bit are the shows they have near the big hat. I don't go to them special, but we often stop for a few minutes. To me, though HS, has the least special theming.
VERY late at night (thinking mostly this happens at MK) the park gets a special kind of feeling. It's a little crazy, it's a little bit comraderie. It is also a LOT more free-for-all- when it comes to flash photos on dark rides. I suppose though if most th cars around are empty. it's slightly more forgivable. There's a certain feeling though that nobody in MK at 3am is a first timer.
OH, and another late night tradition for us is a late night cookie. Gone are the Toll House cookies form Main St. But there are cookies to be had in Liberty Square, at the Villains shop in HS, Norway bakery in Epcot, sometimes over by Energy as well. There are other sweets available pretty late as well. Like the Main St. Confectionary is open late and has M&M's, rice Crispie treats, fudge, etc.