Usually RPGs always had casinos that mostly consist of card and dice games, which is nice, I think I spent just as much time in Lufia 2's casino as with the rest of game, but having (what felt like) a full blown theme park in a game really was mindblowing. And it was integrated into the story, too.
Though nowadays, when I go back to it, I usually don't really know what to do there, most of the stuff in it is pretty boring. And I think I never really got the highest score you needed for something in that rollercoaster game.
Well yeah, some of the magic is dispelled once you become older I suppose.
There are actually not a lot of interesting things to do in Gold Saucer besides the Chocobo Racing and the tournament fighting and the occasional mini game in the arcades(I like the basketball thing myself). The rest of the places like the Ghost House/theater and stuff are not very fleshed out.