My DW and I have been on our 15th, 20th, and 25th anniversaries on DCLs. Multiple other trips to WDW, VB, and HHI without the kids. WDW and the other options at the resort/area are not just for kids, try some of these options for other than the parks:
sports: golf, fishing, RPDE, marathon, bowling, ESPN Club, WWS/ESPN Zone, etc
shopping: DTD, area outlet malls, large scale malls
drinking: Jellyrolls, Raglan Road, monorail tour of resorts, walking tour of resorts in the Boardwalk area
movies: DTD 24 screen theater some with meals served by waiters
night clubbing: Jellyrolls, Atlantic Dance, Raglan Road, Citywalk
resort tours: monorail tour of resorts, Boardwalk around the lake tour of resorts, AKL/AKV
offsite: Gaylord Palms Resort, Citywalk, swamp tour
If you are going to go, go all out and have a great adults-only time.