If you liked Grande Vista you'd probably like Cypress Harbour as well. The resort preceded Grande Vista but has be completely refurbished recently - completed early last year I believe. Because it's older the landscaping is more mature than at Grande Vista. That may be the only reason but in my opinion CH has a more laid-back feel to it than GV. And the staff at CH is most helpful group of people that I've come across at a Marriott timeshare - much more accommodating than the staff at GV.
Now, on the other hand, there may be issues at CH for a party of 5 adults and a toddler. As opposed to GV, where there are 1, 2 and 3 bedroom options, CH only has two bedroom units. And the configuration of the second bedroom can be a bit crowded if both the queen bed and the queen pull out sofabed are being used. The other pull out sofa bed in the living room might make the configuration more viable but there's no privacy for whomever sleeps out there in the living room.
For me, if the configuration works for you, Cypress Harbour would be the choice. However, if that doesn't work for you, you might also want to consider Imperial Palms. IP's units are all three bedroom villas. These villas have also been recently refurbished and look to be quite nice - at least from the pictures. The setting isn't as nice as either Grande Vista or Cypress Harbour and you'd share facilities with people at Royal Palms, possibly Sabal Palms and you have access to facilities at the adjacent Marriott World Center. Go to their site -
http://timeshares.marriott-vacations.com/ownership/resorts/marriott-imperial-palms/overview.html - for description and resort map. The location is quite good if you're planning to go to Disney.
Some may say that Harbour Lake is perfect for younger children because of the very nicely themed pool areas and that's true but the pools at the other Marriotts are very good too and the interiors are a little bit more upscale than at Harbour Lake.
Enjoy your stay!
Dick Taylor
