Would Valley be a good place to start exploring the manic tracks of TrackMania? Or are players scattered to these different expansions so that they are all the same?

Unfortunately, 2011 is the only really good starting point for trackmania.

Sad, but true.

Damn, this seems like a cool game. Why would the developers make such a weird design choice with these different "games", DLC track / car packs wouldn't work with TrackMania?

Yeah, I'm annoyed about the same thing. After watching Jeff play Trackmania enough times I finally want to try it out, but it seems like it's been kind of destroyed by the release of Valley. I'm thinking I might just jump into Stadium and see how the Giant Bomb server is doing over there.

There isn't a Stadium server at the moment but I could swap my Valley server over to Stadium if there's enough interest. It's really hard to judge anymore, though, all three games are pretty dead.