In case you don't know, there's a themepark locations slightly southeast of Gecko. When I heard about this, I was so excited that I dropped what I was doing and rushed up there. To my dismay, there was little more than the remnants of a track, a few buildings, and a nuka cola machine.
What I suggest is that it become more of a dynamic place. I don't mean dynamic objects like something's added every five minutes or moving, but more like something players can actually contribute to. First, an NPC needs to be spawned there. He will introduce himself as a wealthy man who is good with mechanics and has taken an interest in fixing the place.
He will need very large amounts of junk, wood, tubes (yes they could be useful again), minerals/ore, electronic parts, metal parts, MFCs, SECs, pretty much everything. You can bring him any of these for some kind of reward--nuka cola, caps, train tickets, could be anything really. When he gets x amount of junk, wood and minerals, the map literally respawns with new buildings. When he gets a certain amount of other parts, let's say the rollercoaster gets fixed (another map respawn). A few more rides could be added (though I don't see them doing much more than looking nice unless they were 3d and actually moved) and then the buildings and stands he made start being filled with merchants (of course we'll need guards too, because PKs have no self-control) and maybe even carnival games that are either mini-games (which would take a bit of effort), or stat based, but with cooldowns on each game.
Honestly, the specifics aren't what I'm concerned about. What I think many people would really enjoy is things in the wasteland changing based on their actions, because ATM you have TC and there's not much else you can do to affect the actual world in FO.
Always open to suggestions/criticism/dev input.