I highly recommend the Chandelier bar if you are looking for an upscale night out without going to a night club. It's located in the Cosmopolitan and has multiple floors. The bar itself it's decorated from floor to ceiling in crystals. You can't miss it once your on the casino floor.
The entire atmosphere of the Cosmopolitan is upscale. It unlike any other hotels I've experienced in Vegas. This bar is no exception. We sat on the second floor overlooking the lower lounge. When we arrive we found two seats at the bar. Be aware all levels quickly fill up. Second thing to note is the drinks are not cheap. Be ready to drop some cash at this venue. Bonus - the drinks are worth your money. I had one of the biggest glasses of wine during my time in Las Vegas here. The bartenders are super friendly and add to the ambiance of the place. We ended up going back for a second night in a row!