i lived in singles and suites (10 different housing situations throughout my college career, which included summers as well... i never wanted to go home) 🙂
if you have a single within a suite, it rocks. you meet new people and you get a lot of fun visitors -- which is highly difficult when you're living alone in a single.
$500 more for just a single? i'd never do it. you'll be lonely and life in a single sucks. i have friends who used to be so depressed since they didn't encounter the suite style living thing and had the single dorm thing instead. it totally sucked for them and you felt bad because most of them never really got to know anyone else on campus since they lived all by themselves. a suite increases exposure, and if you want to meet people, that's the way to do it.
in my college, there were pros and cons, of course:
suites: have kitchens shared by only your suitemates, have a bathroom shared by fewer people, are more social
singles: have a kitchen shared by all your floormates (and is consequently gross), have a bathroom shared by like 20 people (also smelly and gross, and funny people sing in the showers), and give you lots more privacy
which one would you choose?