I'm sure Jarvis will have a more thorough answer for you than anything I could say. However, I'll give you my opinions since I was just there a few weeks ago...
I MUCH prefer IOA to the Studios. When we went, we bought tickets that were buy 2 days, get the third free. We spent two of the three days at IOA, and the other day was mostly spent at the Studios, with just a train ride to IOA so we could experience the Hogwarts Express in both directions. The rides at both incorporate a lot of special effects, moreso at the Studios.
My favorite rides are: Rip Ride RockIt (look up secret song codes online for a wider array of songs to choose from)
Hulk (this is probably a lot based on nostalgia for me because it holds great memories for me from a visit with my brother)
Harry Potter Forbidden Journey
Gringott's
Dragon Challenge
I love all the rides and theming in Seussland, but since you won't have kids with you, you may want to skip that.
Both "kiddie coasters" are fun little rides, and you don't have to have a kid with you to ride them. Hippogriff is convenient to all the other Hogsmeade stuff, so you won't have to go out of your way to ride it. Woody Woodpecker is very much in a kiddie area, tho, so you may not want to go out of your way for it unless you are a credit whore (like me...). It is very close to ET, though, so if you want to ride ET, it's an easy little detour to get to it.
As far as food goes, we usually eat across the street at the Ale House or at TGI Fridays.
