if you're willing to spend the money and walk/bus or have a car, go for clark kerr. it's nicer but farther away, that's where all the athletic people stay, so it's the best. bowles is a male only dorm that's quite old. foothill is pretty nice as well, plus it's close if you're in engineering or chemistry. the units are pretty much your average dorm, i'd stay away from freeborn dorm (gay,lesbian, nondrinkers ie freaks, I wouldn't stay there) and i guess the whole Unit I dorm, since Unit 2 and 3 have better food (it's the same food, just cooked better). you'll find that the Units have a lower quality than the others, hence the price, but you can eat anywhere you choose. Also, i wouldn't get a triple, if possible. As far as co-ed, it doesn't really matter, since the floors are staggered in the Units, unless of course you don't leave your floor...
As far as choosing Berkeley, I'm not sure if you're from California or not, but expect to live outside the dorms after your first year in a crappy place paying a ton of money unless you join the fraternities. You can also try the International House as a junior/senior.
For a meal plan, I'd just stick to the regular plans not the $ crap to spend at the overpriced places on campus. If you're picky, get the fewest meals, usually meals on the weekends are leftovers, so I'd get a 13/15 or whatever depending on whether you're going to be eating breakfast