You can take the Straßenbahn around Ring Road, from which you can see most the major spots (city hall will be one of those spots along the way). Get a day pass and hop on and off as you wish.
Make sure you get one of the rooms with views of the Strip and the Bellagio fountains. I think it's the west tower that has the best views. If you get the corner wrap around balcony it's really a breathtaking view.
We ended up getting a great deal at the Luxor, since it's March Madness, the rooms almost doubled in price. We were lucky to get three nights for under $300. We did look at the Cosmo and I definitely want to stay there one of these days.
This one I really liked. My suggestion is though, that you visit Krakow first (Wawel), and then go to Zamek Krolewski. It follows the kings chronologically, and is really interesting this way.