I am looking for positive and negative reviews for the following places in Orlando:

Sheraton Vistana Villages
Marriott’s Grande Vista
Marriott’s Cypress Harbour

I have the opportunity to stay a week in one of these places and I can’t decide which is best because they all have some good and bad reviews on travel advisor. Please let me know any personal experiences!!!

Also, we are not buying a time share but we are renting one week from a person I work with. What are some things I should be aware of when renting a week from somebody? What things should I look out for to make sure everything goes smoothly and is legit? Any tips would be great from anybody who owns a time share or who has rented a week from somebody before.

Thanks and please answer if you can help me with any of my questions.
Sheraton Vistana Villages is not the same as Sheraton Vistana Resort (this is the older place).