I have stayed at Sheraton Vistana Resort, which is right around the corner from the Marriott World Center complex, twice in the last 3 years or so. SVR is well-maintained and pretty recently renovated. I definitely recommend it and love how close it is to WDW.
here is a link to a recent page of the thread with some pics:
http://disboards.com/threads/the-sheraton-vistana-resort-thread.3148502/page-35
here is the first page of the thread with links to more info:
http://disboards.com/threads/the-sheraton-vistana-resort-thread.3148502/
here is the allears link:
http://allears.net/acc/faq_svistana.htm
(There is also a Sheraton Vistana Villages resort which is farther from the Disney parks - more toward the SeaWorld/Universal area. It also has a great reputation but I have not stayed there.)
I have stayed at the Marriott Royal Palms resort (within the Marriott World Center complex) and it was recently refurbished. It's a great location and Marriotts tend to be very nice (so long as they are not at the very end of their refurb cycle.)
I have a reservation for Sabal Palms coming up but all I can tell you is that I got an email that they will be undergoing construction:
"Currently, we are in the process of enhancing the façade of the buildings. As a result, you may experience some construction related noise and contractors working in the area. The project will take place each day from 7:30 a.m. to 6 p.m.
We anticipate that this enhancement will not affect your vacation in any way and we will notify you if there are any variations in the work schedule.
Thank you for your understanding! We hope you are looking forward to your stay at Marriott's Sabal Palms!"
So I would recommend SVR in this case if that is what you have as an option. Both timeshares will probably be fairly large and spread out. (You can ignore the timeshare sales pitch by not agreeing to go to a sales meeting/breakfast and ignoring any special gifts at check in.)