I'll go through attraction by attraction:
UNIVERSAL STUDIOS:
Jimmy Nuetron - queue not themed, take express
Shrek 4D - queue not themed, take express
Twister - queue is themed, but can be seen through express line
Mummy - take regular line at least once.
Disaster - only things viewable in the regular line are the set pieces, not missing much
Jaws - queue is themed, but can be viewed from express
MIB - take regular line once
Simpsons: Take express line, regular line is just a bunch of switchbacks
ET - both lines go through the forest, so take express
Woody Woodpecker - regular line does have a view things to mess with under the coaster, but they're not worth waiting over 10 minutes for.
Terminator: Take express
ISLANDS OF ADVENTURE:
Hulk: most of the theming in the queue can be seen from the express line, however the theming stops when the express goes outside, under the final brakes and up the stairs, so it's up to you.
Storm Force: Take express line
Doctor Doom: The ride is so short, the wait won't be worth it, but the regular line is among one of the coolest in the park. if it's a long wait, take express, but if you want to go in and see it, you can. it's a good queue line.
Spiderman: the express line is actually better than the regular line.
Popeye and Bluto's - regular line is long (as in a long walk) but it's got some cool stuff you'd miss if you took the express line
Ripsaw: regular line has some cool stuff, express takes you down stairs onto the ride
JP River Adventure: take express, not much to see in the queue
Dueling Dragons: take the regular line! this one is amazing, by far the best in the world. It'll be a good 8 minute walk, but it's amazing
Poseidon's Fury: take express, it's right next to the regular line anyways
Sinbad: it's a show, you just get priority seating
Sky Trolley: the only thing in the regular line to see is the big spinny thing in the regular line, that's basically it.
Caro-Suess-el: take express, may not even need it
One Fish Two Fish - take express, not much to see in regular line
Cat in the Hat- take regular line so you can see the house and the sayings on the wall.
It's up to you really. If you'd rather just get on the ride and not have to see the themeing or whatnot, then the express is the way to go.