The Bellagio is really seperate from the other AC casinos, by about 2500 miles.
I'm pretty sure you're referring to the Borgata. Borgota is a VERY expensive hotel/casino. But it's also VERY nice. The Tropicana did some extensive remodeling as well as the Showboat. Both have nightlife (shows/bars) as well as your gambling entertainment. Wild Wild West hasn't changed much in the past 10 years, so as a result has lost some luster.
And everytime I go down there I've got to stop at the Irish Pub (St. James Place and Boardwalk.) Good & inexpensive food/bar.
