Ah, Vegas...my second home. :) In truth, we looked into moving out there before we had our first son. I've been there about 15 times since 2002 (I don't even gamble that much). It's just a great place for a short trip to escape from "real life". I've stayed at Luxor, Paris, Bally's, Excalibur, Monte Carlo, MGM, NYNY and New Frontier (gone, now).
Luxor - nice, but high tables. On the Strip, but a bit of a walk to get to the main hotels. I wouldn't stay here again, personally.
Paris - attached to Bally's, pricey rooms. Personally, I wasn't that impressed and wouldn't pay the extra $ for the hotel.
Bally's - good price, great location - across from Bellagio where you can see the Fountain show (a must). Nothing too exciting, though. But, I'd stay here again without a doubt.
Excalibur - ok, very good prices, but a bit older. I've stayed here a few times because they have the best rates and they were one of the first casinos to have "War" as a table game. Fun. My husband doesn't like it, though and wouldn't stay there again.
Monte Carlo - one of my favorites, actually. I've stayed here a few times, too. Not very crowded, but a good location. When I went this past September, they had added a really cool bar/Mexican restaurant to the front of the hotel and it made it much more "lively".
MGM - Another favorite. I just love the hotel itself (and they have War, too!). The room we had was great, but the hall ways are the longest I've ever seen in my life. We were at the beginning - thankfully. My favorite part is they have the MGM Lions to watch. I could sit there and watch them forever. And it's free. Lol.
New York, New York - I stayed there this past September and it was ok. Fair price, good location, nice rooms, but not one of my favorites. Our room was over looking the roller coaster (it's fun, try it) and we didn't hear a thing.
I've done two "sister-trips" with my sister and we loved it. MGM has an amazing pool area. Monte Carlo and NYNY have pools, but they are in the shade for some of the day. Bally's pool is huge.
I've been to Vegas in just about every season, too. My husband and I go during March Madness for the NCAA Tournament (and our anniversary). It's a ton of fun, but not very hot yet. We don't even hit the pools then, usually. June-July is hot as HELL (literally!). But, I don't mind. We sit at the pool during the day and play at night. September this past year was great, but it was hot. I think it was unseasonably warm, though. December is chilly. I actually had to buy a jacket when I was out there.
We've never rented a car - but we've thought about it. We just have our days so filled that we don't leave the strip. For a first trip out there, I would recommend doing the same. There is SO much to do that you don't need to worry about a car. There are cabs EVERYWHERE and even a tram now on the MGM side of the strip.
Ok, I could go on and on here - I didn't even get into where to eat! If you want more information, send me a message and I'll answer any questions you have.
T.