Adventure Land in general gives me the feeling. On our first trip to WDW (our honeymoon in 1980), we first went to Adventure Land. We didn't really plan it in advance that way, just turned in that direction first. MK was the only park back then and much has obviously changed. The first thing we ever did at MK was Tiki Room. Until they updated it, it was still our traditional first thing on return trips. Now our first thing is Splash Mountain. However we still turn and go over the Adventure Land bridge when we reach the end of Mainstreet on our first day. It just feels right.
A previous post mentioned looking for some of the old paint job in Tomorrow Land. I look for that as well for some strange reason. When riding TTA, we talk about what the old T-Land looked like. Back in 1980, we thought the old T-Land was very cool.
Until it closed, going to River Country also produced the feeling. It was the first waterpark we had ever been to (it was the first themed waterpark anywhere to the best of my knowledge). We loved it, we told our friends all about this great place to swim and all the wild slides and such. Now days RC would be a yawner compared to other water parks.
Another thing would be riding the monorail. On our first trip we drove to the park and boarded at the TTC. In essence our first attraction was the monorail. I still get that feeling of anticipation on the monorail.
The only other thing I would mention is walking into Epcot. We went to Epcot right after it opened, it was simply amazing. The place was shiney as a new penny, and everything was ahead of it's time, it was perfect in every way. Spaceship Earth left us in awe. Nowdays, you read on these boards how many feel it should be done away with or seriously updated at a minimum. I still love that ride, just like it is.