We've done Bellagio a few years ago & the Venetian last year - not a lot in it, but Bellagio just heads it for me.
I suppose its just personal preference & cost really.
The first stay in the Monte Carlo in 2013 was just to keep the cost down as we were on a triple state holiday (Chicago, Vegas & DC) so were looking to keep cost down.
The second time in 2016 we had taken a small detour into Vegas while driving Route 66 so opted for a fountain view room on the front of the Bellagio.