I went here on a Thursday night, and much to my surprise I had a lot of fun! We got there after 11pm which was a big mistake because there was a huge line to get in. By some grace of good luck, one of my friends had stayed at the Wynn earlier in the week and had a VIP card, which we decided to show to them and promptly were let in right away w/o having to wait in line!! The vegas club scene is fun as hell, but also annoyingly frustrating at the same time. Make sure to get there by 10pm and have a good ratio of girls to guys if you want to get in at a decent time!
The inside of Tryst is very cool, with the dance floor in the center and a huge loungey area surrounding it w/ music blaring throughout. The entire place was packed, and they played hip hop and house the majority of the night, w/ some old school beats thrown in. I liked the music a lot, but the DJ that night could have done a much better job mixing. He'd play one song and change it 10 seconds later, so it was virtually impossible to keep a steady groove going!
Perhaps the most unique thing about Tryst is the waterfall visible from the dancefloor. It's quite a site and all lit up at night. There's also an outdoor area to dance and lounge which is really best to enjoy during the summer season. All in all this is a place everyone has to try, just get there super early and have some girls with you and you'll be guaranteed a good time.