I hadn't been to Magic Kingdom in over 10 years because I felt it was too "young" for me...
I felt like I preferred more "adult" entertainment. Now as I'm a little older (mid-30's), I realize how much fun there is to be had here, especially if you go when there are low crowds.
We were here the week after President's week, and boy did we time it right! We were chosen as the "family" to open the park that morning. We were a party of six adults and we were thrilled...we jumped up and down and yelled like kids, high-fiving! Once we did that, we proceeded to Frontierland, unlike 80% of the mass, which went to Tomorrowland. We were the first (and apparently only) to arrive at Big Thunder Mountain Railroad. Four of us took the first two cars and the other two took the rear car, and off we went! It wasn't quite as thrilling as I remember it, but it was a once-in-a-lifetime chance to ride it all by ourselves!
From there we went to Splash Mountain and proceeded around the park in a clockwise direction...when we got to Space Mountain, it was a walk-on...three times! Each time was better than the last. (I don't know about anyone else, but the right side just seems more thrilling!)
Astro Orbiter was a blast, simply because I went on with a friend who is scared of heights and I took our rocket all the way up! What a view! Even if you are going a little fast to take it all in. My friend didn't see too much...her head was down.