What kinds of activities do you have planned?
The Paris is one of the nicer hotels on the strip. It smells pretty. I actually won $200.00 on one of the coin slot machines after two tries. Your lady will love it there. Another nice hotel is the MGM Grand, if you're trying to make your girl smile.
But if you plan on doing a lot while in Vegas, I would recommend staying at one of the less costly hotels on the Strip. For example, the Excalibur sometimes offers $29.00/night stays on expedia or their own hotel website, as does many others. The reason for choosing any inexpensive hotel if you have plans to do a lot is that in Vegas, you will never see the inside of your hotel very much, except for the time you spend sleeping, and it's a place where you will want to sleep much less than you usually do. There's tons to do and it's all so fun and stimulating, and you lose track of time.
I'm one who needs my eight to nine hours of sleep and often naps. In Vegas, I wanted to keep going. I slept maybe 3-4 hours a night and didn't feel tired at all. And if you stay on the strip by the major hotels, the Paris, New York New York, Caesar's Palace, the Venetian, the Mirage, etc..., everything is within walking distance.
And there's so much to do and never enough time to do it all. Anway, post photos when you get back and let us know how it went. Have Fun!
P.S. Be sure that you and especially your girl brings really good walking shoes. I brought all 4" stilletos that I usually walk in at home, but they weren't practical there. There's so much enjoyable walking in Vegas, but you and especially she will regret not having the kind of shoes that are comfortable to do a lot of walking in...