Don't go to Club Rain - the line is too long and it is not worth the wait because it gets too crowded inside but it will be crawling with all sorts of people because of that show on MTV.
I suggest Drei's (sp) - gamble until about 1am (line starts around midnight or 1am) and get plenty drunk and then head to the Barbary Coast for their after hours club (Drei's). I always try to head over there while I'm in Vegas - hot girls and as long as you get wasted before you head in then you will only have to pay the $20 cover and buy a few drinks ($8-$12 a drink).
Lastly, the other place to go is Baby's (at Hard Rock). This is where it will happening during Spring Break - people don't go to Baby's unless they are under 35 usually under 30. Hard Rock is supposed to be the Spring Break getaway.