Besides DVC, I own Hilton, Hyatt, and Marriott. They all complement each other perfectly.
DVC is the most flexible, and is great for on-site WDW visits. When I stay at WDW DVC, I don't even go off-site for anything.
Hilton is nearly as flexible as DVC. I always use my week at Sanibel Island, and my other points I use within the Hilton system for Hawaii, Las Vegas, and even Orlando. When I stay at an Orlando Hilton, I often go to Universal, Seaworld, and off-site restaurants and shopping. Hilton also has last minute (30 days or less) reservations at a low cost for anything that's available. Right now I'm using that perk at Miami Beach, and next week will be at Marco Island.
The Marriott is in Palm Springs, and usually I use it one year, and trade to another Marriott the next. Marriott has by far the most resorts to choose from. Also, the Marriott comes with II membership, so I can take advantage of the II getaway weeks.
The Hyatt I use to trade within the Hyatt system. They have resorts in more unusual places. This trip will include stays in Key West and Bonita Springs (Naples). I've also used my Hyatt points to stay in Puerto Rico, Lake Tahoe, Beaver Creek, Breckenridge, San Antonio, and Sedona.