The three Marriotts and the Sheraton Vistana Resort are among a group of the best maintained timeshare resorts in the Orlando area (the other Sheraton and Marriotts, Hilton Grand Vacation Club resorts and the independent Cypress Pointe Resort - IMO - are also in that group of very well maintained resorts) so those are very good resorts to have to choose from. You won't find a lot of difference in 'age' as these resorts have all gone through fairly extensive refurbishment recently.
As you might imagine, timeshare resorts in the Orlando area, in general, target families. So you'll see a lot of amenities at these resorts that are appropriate for that audience. It's true that Marriott's Harbour Lake is more targeted at families with younger children because of the type of pool and water feature theme there (the villa accommodations are also a little less impressive than at other Marriotts, too) and Grande Vista tends to skew a little toward the golf crowd - at least in terms of owners there - and what about the person who said they were yelled at for walking on the grass??, were they actually cutting across the golf course, lol? But when we've been at Grande Vista the cross-section of guests has been quite broad - the Plaza del Sol pool area has a section that's specifically targeting young children. Grande Vista does feature several on-site eating options including a sit-down restaurant at the golf clubhouse (somewhat limited menu but it's nice). And there's a nice bar/grille area at Plaza del Sol called Copa Loca in addition to food options at the marketplace store and nearby Pizza Hut Express at the Village Center pool area. Cypress Harbour is my family's favorite of the three Marriotts - and also the oldest of the three in terms of original build. Like our experiences at Grande Vista, we've found this resort to have a broad cross-section of guests. It's a little smaller than Grande Vista and the setting seems more old Florida-like because of the mature landscaping there - nice place to relax. Food options are limited to the Pizza Hut express/Galley Grill/Marketplace Store that are above the main Clubhouse pool area and next to the Pavilion Bar and check-in building. I'd guess $25 - $30 for a taxi from these to Epcot.
A drawback for all of these Marriotts is that there are no off-resort restaurants that are in truly walkable distance from them. Cypress Harbour and Harbour Lake are on Westwood Boulevard in the SeaWorld neighborhood, Grande Vista is tucked off from International Drive - also roughly in the SeaWorld neighborhood - but a ways away from restaurants.
Sheraton's Vistana Resort is on Apopka-Vineland Road, closer to Disney property than the Marriotts on your list. This is one of the largest timeshare resorts in the Orlando area (I think that only Orange Lake Resort in Kissimmee is larger) and was the site of our first Orlando timeshare resort vacation back in the 1990s. Nice resort that recently underwent significant refurbishment in each of the sections so it was like-new coming out of that work. This is also a family-oriented resort with lots of children's activities and tends to skew a little younger than Cypress Harbour and Grande Vista, I think. There are several restaurant options within a mile of this resort (Santa Fe Cattle Co, Lone Star Steakhouse, Landry's Seafood, Bahama Breeze, Golden Corral, maybe a few others) but most of them are at least 3/4 of a mile away. There's a CiCi's Pizza, Wendy's, Starbucks and likely a couple of others that are a bit closer to the resort.
All-in-all, good choices in terms of the resorts that you're looking at so you likely won't have any regrets with any of them.
Dick Taylor