Kristin, he sure has grown up .... and Up ..... and UP!
My advice having three now 20-26yo is to keep the lines of communication open, remember however big/old/smart they get that they still need you parents as role models, and to frequently tell them you love them. Don't be afraid to say it in public, in front of their friends, or between the two of you. And some times they need tough love but keep doing the prior three things at the same time.
Keeping this Fort related,
By the time your son hits our ages, I think the Fort will still be there but at what cost?
Disney is not raising the prices to attempt crowd control either (a theory floating around the DIS). I hope my kids have many memories not just from the parks but all the times at the Fort.
Bama Ed
PS - and Teamubr, give it a few years and then when they are out on their own and making life decisions, suddenly you're going to sound a lot smarter than you do now. So give it time. But your DS has been a nice young man every time I've ever been around him so I think you're being just a wee bit harsh.