We have taken our kids to beaches, on a cruise, Disney, cities, etc. Last month, my parents rented two lakeside cabins in TN for the whole family to enjoy. It was our second favorite vacation ever. That was for EVERYONE. My parents have traveled extensively as well and it may be their top pick!
Fall Creek Falls State Park...look it up! It's about 2 hours east of Nashville (which I also highly recommend). There is mountain climbing, BEAUTIFUL falls, horseback riding, zip lining, fishing, golfing, and so much more. It's in the top 5 parks for the US! And this recommendation is coming from someone who was NOT an outdoor person before that week - now I'm itching to go back!
And my husband didn't want to go on a cruise either - 21 years in the Navy does that to most people. But we took our kids January 2013 and it's still our top vacation. I haven't met one person who doesn't love them...but I know they are out there. So it might be worth doing a short one just for them to get the experience.