We have been Vidanta World (my term) owners for a long time, and from 1999-2006, we had just Mayan Palace 2-bedroom units. Since becoming GM & MP owners at the same time, we did exchanges our MP weeks and used our GM weeks at one of the GM resorts.
Our family travels with us for Thanksgiving every year and my D-I-L really wanted to go to Hawaii in 2005 because their 10th wedding anniversary would be in early December. I deposited 3 weeks in March 2002 (because everyone said they would be up for Hawaii) and put in an RCI request for Hawaii - I did not specify a specific island - just wanted to go to any one. In October 2002, I got an email that I could get 3 units for the same week for Thanksgiving 2005 at a resort in Kauai. So, 3 years out! (We had an awesome vacation with 12 adults and a 5 year old.)
In 2007, our youngest son and his wife wanted to go to Maui for their honeymoon, but I could not get a week closer than 2 years out. They said they would go somewhere else for their honeymoon and do Maui for their 2nd anniversary. I snagged the week, and then when it got close, they said they could not afford to go, so we used the week for ourselves.
So, as with all exchanges, you must be flexible and plan a long time out. Deciding you want to go for a specific date and island takes a lot of planning.