We have stayed at the Marriott Grande Vista and really enjoyed it. We didn't stay on a tour or deal, just paid the rack rate for a 2BR villa (actually, DH's boss paid!). We liked it a lot, but didn't "love" it. I would like to try Horizons and Cypress Harbour while our girls are still young as I think they would enjoy it.
The price you saw seems pretty good, I think we paid $260/nt. for a 2BR villa. But, there are member referrals and timeshare tours for like $400 for 4 nights. If you need more info, just pm me.