Magic Kingdom:
Walt Disney World Railroad- I love it, but I've also loved trains since I was a kid.
Peter Pan's Flight-I think that unless you get a fastpass or the line is extremely short, you can skip it.
Dream Along With Mickey- Unless you get a shady spot or a cloudy day, skip it.
Snow White's Scary Adventure- It's cute.
Dumbo- I actually still haven't done this

Winnie the Pooh- I go on this every trip, but I also LOVE Pooh Bear.
Astro Orbiter- If you go, do it at night. It's a GORGEOUS view.
Tomorrowland Transit Authority- I really like this

Carousel of Progress- I'd do it just to do it, but you could probably skip it.
Wishes- You've never seen Wishes???

WATCH THEM OMG.
Hollywood Studios:
Sounds Dangerous- It's usually closed, so don't fret if you skip it. Also, the headphones are usually pretty gross.
Indiana Jones- It was fun for me, but I'm also a big action movie dork and love working out how they do the effects.
Lights, Motors, Action- See above.
The Magic of Disney Animation- It's cute, but you could probably skip it. It's mainly a tour with a drawing class at the end.
Fantasmic- It's fun, but if you do it, do the viewing package at one of the restaurants. That way, you don't have to stand in line for hours.
Animal Kingdom:
Pangani Forest Exploration Trail- My mom loved this.
Wildlife Express Train- She liked this, too.
Habitat Habit- And this.
Conservation Station- And this.
Affection Section- This is cute.
Maharajah Jungle Trek- My mom loved this, as well.
Kali River Rapids- It's fun, but depending on the weather, it'll either be a skip it because it's cold or skip it because it's packed.
TriceraTop Spin- I didn't do it because I can't do spinny things.
Epcot:
Ellen's Energy Adventure- Eh, I always skipped it.
Honey I Shrunk the Audience- I think this has actually been replaced by Captain Eo at the moment...
The Countries, minus Japan & America- Do them, definitely!
Maelstrom- Eh, I could skip it.
Illuminations- I love Illuminations, but not as much as I love Wishes!