I don't go on the two worst water rides (in comic book area) so for me there's not much to do in IoA. At IoA you have Hulk, the bungie tower ride thing next to Hulk, Spiderman, Kong, Jurassic Park floaty ride, Forbidden Journey, and Dragon Challenge. I have not been on FJ since they switched the picture to decrease motion sickness so depending on how that goes I may start riding that more than once a week while on vacation. There are other things to hang around and look at or go to the shows if you want but nothing you would need EPs for. Most of these also have single rider lines. Now that I think of it when I'm at IoA I usually just ride Hulk a bunch of times then maybe once on Kong and Spiderman if the lines aren't bad.
Studios has Minions (always long lines), Shrek 4D, RRR, Mummy, Transformers, Jimmy Fallon (soft opening), Gringott's, MIB, Simpson's, and Terminator 3 or 4D. Also a lot of single rider lines. My normal morning here would be a bunch of rides on Gringott's, then two or three times on MIB, then single rider for Mummy, RRR, and Transformers. If they have early entry I go to Minions once then to Gringott's. RRR tends to give me a headache which has cut down on my repeat riding.
If you like riding things more than once you will likely still be able to w/o EP - just go in single rider your second time. In my experience Kong, FJ, RRR, Transformers, Gringott's, and MIB are down more frequently than you would like if you're only there one day. Hopefully you get lucky and everything is working good the days you're there. My worst day MIB was down then to Gringott's which was down and then to Kong which was down. We left the parks at that point. My husband likes at least one trip to a flea market so that was our day.
There is a night show at Studios that I watched once about five years ago. They project old movie clips onto water and have some fireworks. I'm sure you can check it out on
youtube. Now if I'm there at showtime I use that opportunity to go to HP when it's much less crowded. Also a good time for one last ride on Gringott's.
Remember you can buy EPs in the park after you check out the crowds and the rides. Regular EPs are only good to ride once and they're pretty expensive.
March is spring break for some so it will be more busy than other times. Where I work near Charlotte spring break isn't until mid-April.