Dude... I took my wife to a surprise trip to Disney Animal Kingdom and Universal Studios last Feb 28th - Mar 2. We had a BLAST!!
Go man... it is fun. Even if you're an adult. What you enjoy there will change.... but its still fun. Maybe 18 is an awkard time to go... you're past your kid fun stage... but you aren't at that married lame-ness kind of fun stage

. But I think you'll have a good time....
Plus, maybe you can snake out to Bush Gardens, the beach or whatever.