We've done 4 cruises on Mardi Gras (3 times in a balcony cabin and 1 week in an inside) and 2 weeks on Vista (inside on Lido). During our second week on Vista, we came to the conclusion it just wasn't our favorite. While we had a great time, there were days that we were just tired of all the people. It seemed to be more crowded than Mardi Gras, probably because MG is such a big ship and has so many more options for both bars and outside areas. There were things we loved about Vista - JiJi and the lasagna at Cucina, the atrium bar to name a few. If we ever cruise on Vista again, we'll be looking at the Havana area.
We have 2 upcoming cruises on Mardi Gras and 2 on Venezia (I know, I know).