Jeans, dress shirt and dress shoes is fine. You'll have no problem getting into any clubs in Vegas like that. I've been to pretty much all the big clubs there and that's what I always wear.
I recommend you hit up some pool parties too. Encore beach and Wet Republic on Sunday is crazy. Tao beach isn't bad as well but I've only been there on a Friday and Sat. I just got back and I miss it already
