Luv LUV LUV the Go rooms! Rio rooms have been decent to me in the past, but the GO rooms are sooo cool. Luv the linens in the Go rooms as well, and I'm admittedly a linen diva. And yes, plenty of room for a cot, you can just move the small couch around to accomodate. I was in a 2 bed GO room just a couple of weeks ago.
That said, CLV has a good point, not so fun to drive back and forth all the time. The last time I was at the Rio during WSOP (as a spectator, of course) the parking was impossible.