Oh hell yeah, you're doing this... and here's my advice on how to do it the BEST way and even save a little money.
First, you're going to get yourself a Living Social deal (or Groupon - whoever is offering the best deal that week), because paying full price is for suckers. Get the cheaper alternative when it comes to time - the 12 to 6 PM ticket. BUT splurge and get the Happy Hour option with that ticket. You've just saved yourself $5 to $10 based on the specials running on the site at the time. * I think our tickets were listed on Living Social for $31.99 each, but I waited until they offered an extra 20% off so we ended up paying around $25 for each ticket - a very good deal!
AND by purchasing the daytime tickets with the HH option, you'll also save yourself a lot of aggravation. Here's why:
Most tourists want to do the High Roller at night. So every "cage", including the few Happy Hour ones will be full. Of People. And probably children. Ick. But if you show up at around 5 when it's just starting to get a little bit dusky, there isn't a line - especially for the Happy Hour "cage" and your party might end up riding alone - that's like having a personal freaking bartender!
We LOVED this attraction. It was awesome to see all of Las Vegas splayed out before us with the sun slowly going down. And that awesomeness was helped by a very healthy pour of champagne by a super friendly bartender. You simply HAVE to go here. It's not to be missed. Even those with heights issues should be calm because they can stay to the center of the cage and the ride is so smooth you don't even really realize when you're at the very top of the wheel.
Bartender we had was very friendly and quite forthcoming with the refills (dropping a $10 or a $20 in the tip jar upon entry will help speed that along). So we had a lovely boozy time. Couldn't ask for a better Happy Hour. BONUS - right off the High Roller, there are lots of options to keep the Happy Hour going just nearby and across the street.
I highly recommend the High Roller as the way to KICK OFF your designated "fun/get wild/sleep late tomorrow" night in Vegas.