We just returned from 10 days at Vistana Resort (May 17-27) and have nothing but glowing reports!! We did request to stay in the Cascades Section after having read all the great reports here on the board and we were not disappointed!
We had debated over one BR or two but chose the one BR for four of us (2 adults/2 kids) rationalizing that all we really needed was a roof over our heads - after all, we'd be at the Parks almost every day. As it turned out, no worries - the one BR was fine. The unit was large - kitchen was fully equipped including what appeared to be brand new appliances, beautiful dining and living areas (with queen size pull-out), screened-in balcony, HUGE private bedroom with Jacuzzi and dressing area. Having only one bathroom could have presented an issue but with teens, we were long out of the shower before they were even out of bed.
The property itself is massive but beautiful - always immaculately groomed. (If you're looking for a quaint little place, this would not be my choice!!) The staff were always pleasant and helpful. The downside, if any for us, was that we weren't able to "discover" all areas of the resort or take full advantage of their events due to our hectic park-hopping schedule. Based on their daily/weekly activities calendar, I'm confident you could be thoroughly entertained without ever having to leave the property. As a matter of fact, I may just do that the next time around!!
In terms of transportation time to Disney, we made it from resort to each of the theme park's parking lot each day in 10 minutes. One day we visited Animal Kingdom in the a.m., went back to the Resort for afternoon swimming, and returned to MGM for the evening Fantasmic performance. No issues whatsoever in moving back and forth. To Universal, I'd estimate 20 minutes. Everything is very accessible once you find where you're going. One thing you will not likely do, other than within the resort itself, is to walk anywhere. With highways/busy roadways "surrounding" the resort, a car is a must for shopping, eating off-property, etc.
Hope this report helps you as much as those of others helped me when I was looking for info. Good Luck!!