re: Bars in Vegas

If only considering the strip consider Mandarin Bar at Mandarin Oriental. Make a reservation and ask for a view looking more north.

Chandelier Bar at Cosmopolitan. Go to level 1.5 and order her a Verbena. It has a Szechuan button. Have her take a sip of the drink and then have her chew on the button and take another sip of the drink. They only make them on the 1.5 level.
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Hyde at The Ballagio. It's hard to beat a view of the famous fountains. If you go before 9pm it's more of a lounge and doesn't have a cover charge.

Once ya'll get a few drinks in your system you may want to check out Carnival Court next to Harrah's. They usually have live bands along with flair bartenders. It's not usually nightclub-like and not usually a problem getting in.

Finally, go find a Groupon for the High Roller observation wheel. They have some pods set up with an open bar. It's a 30 minute ride and provides a good view of the strip. There is never a line for this thing so don't pay full price.