Hi! Thank you so much for your input! Cypress Harbour is in our timeshare bank as well. Honestly we have a 10 day pass so only have about 3 days free in the 2 weeks and we are traveling 10/30 - Nov 14. Never been this late in the year so not sure of weather for pool, etc. Given that we will be out more than in can you elaborate more on Cypress Harbour? Right now there is actually 2 and 3 bedrooms available for our time frame at Grande Vista but I'm going to check Cypress as well. Also, sounds like you are very familiar with Marriott overall -- if your staying at one, can you use the pool at another. Say we stay at Cypress, could we try the pool facility at Harbour Lake?? And finally, how far is Grande Vista/Cypress (less than 20 minutes) Can't remember exactly but I think Sabal was literally 5 minutes to get through the main arch saying you're entering Disney. I'm so confused

-- decisions making is not my strong point!
Once again, thanks for taking the time!!
I think that Ed J is generally right about late October/early November as being pool weather but it can be a little hit-or-miss if late hurricane weather stirs up some rain and wind. And he's definitely right about no pool-hopping between resorts - Harbour Lake, in particular, guards against visitors using their facilities in favor of actual guests.
Cypress Harbour is a dedicated 2 bedroom villa resort - no lock-outs, no larger units, just 2 bedrooms. It's a very nice resort with mature landscaping that helps to provide for a laid-back atmosphere that I'll admit that I really like when we're on vacation as just being there always seems to take that go-go theme park pace down a few notches. The resort was built after the Sabal Palms/Imperial Palm/Royal Palms triumvirate but a few years before Grande Vista. It's a moderately sized resort with 22 three to four story buildings. There's a man-made pond at the center of the main part of the resort that about half of the buildings surround along with the main clubhouse, two main pool areas, resort store, bar and grille. The other buildings are located beyond that prime section with golf course views. Cypress Harbour and Grande Vista offers many of the same resort activities with just a little variation - GV provides some spa services, has a full-service sit down restaurant and provides direct access to a golf course from the resort. In my opinion, one of the best aspects of Cypress Harbour is the staff - they tend try a little harder to please their guests than the staff at Grande Vista. For instance, we've never not gotten the location that we've requested at CH while we've never been given the location that we've asked for at Grande Vista. Both CH and GV have recently undergone refurbishment and are up to date for Marriott standards (though I couldn't help but notice that they were re-doing the buildings on either side of the clubhouse at CH when we were there three months ago).
However, if you can get a three bedroom unit at Grande Vista I'd think you might want that for your party (depending on who's going) particularly if it's two parents, two children and a grandparent or an adult brother or sister as the third adult. That would give everyone some privacy without having to house the third adult with children or on the living room sofa bed. GV three bedroom units are huge for a small party like your's.
On the distances...
Sabal Palms is really close to the Disney welcome sign but the better measure is how far resorts are to the theme parks. Here are the rough distances:
Animal Kingdom - 7.5 from Sabal, 11 from CH or HL, 12.5 from GV
Hollywood Studios - 4.5 Sabal, 8 CH or HL, 9.5 GV
Epcot - 6 Sabal, 9 CH or HL, 10.5 GV
Magic Kingdom parking lot - 8 Sabal, 11 CH or HL, 12.5 GV
Downtown Disney - 4 Sabal, 5 CH or HL, 6.5 GV
Actual mileage will vary a bit depending upon the route but those are pretty sound for comparison purposes.
If I were going to an Orlando Marriott and not planning to use a pool at the resort I'd pick either Cypress Harbour or Grande Vista from your list. If I really wanted 3 bedrooms then GV would be the place. However, if I wanted the most luxurious Marriott experience then I'd check to see if the brand new (first phase opening in June 2010) Lakeshore Reserve has any availability (add about 2 miles to GV for the distances to the Disney properties).
You're not going to make a wrong decision with a Marriott property as they're all very nice resorts so all you have to do is decide whether the Harbour Lake water features for the children, the relative closeness of Sabal Palms or the higher-end luxury of the villas at CH or GV will make for a better vacation experience for your family.
Dick Taylor