my parents just booked a 3br there with an exchange, so I'd like to hear too!
They will love all the space in a 3 bed/3 bath. If you go onto Diamond Resorts site and chose Grand Beach - you can see the actual floor plan and the pictures of the bedrooms, bathrooms and kitchen were completely accurate to what we experienced last August. We loved it there and would return in a heartbeat - I think that the negative reviews that you see on TripAdvisor are from people that stayed in a 1 bed which from what I understand is very small and cramped. The 3 bed is amazing.
We had 2 master bedrooms with king size beds and attached ensuites with separate shower and tub. The 3rd bedroom had twin beds and the 3rd full bathroom was directly across the hall from it. Each bedroom and the living room all had TV's. It was huge with lots of space for everyone. I loved having the washer and dryer in the unit to do laundry.
It is so close to Disney - you turn left out of the resort, right at the lights and drive directly to Disney. It takes 5-10 minutes to get to any of the parks. Wal-mart, Publix and Super Target are just down the road - instead of turning right at the lights - stay straight and Wal-mart will the on the right, Publix at the t-section on the left and Super Target is left at the t-section and a couple of lights down the road.
There were lots of activities at the resort - they had a movie night, karoke night and lot of fun things to do in the evenings. We did not participate in the activities as we had a very busy schedule visiting Disney, Universal and SeaWorld. We did enjoy both the pools and met some great people.
Your parents will love their stay at Grand Beach. It is very clean and quiet. Tell them not to waste their time doing the timeshare presentation though - I wish I would have never attended it. In the past year, I have received numerous calls from them trying to get me to come to another one of their resorts - I am talking 3-4 calls per week and one week, I got 10 calls - it is very annoying and frustrating. After they check in, they will be sent over to the activities desk to get their parking lot ticket - tell them to just get their parking ticket and do not do the timeshare presentation.