It seems to me that the point of this is really to have terrain be more unique. As it stands, all continents on a given map type are usually identical. Maybe there's a resource or two different, but it's not that big of a deal. I like the idea of having particular natural wonders that are worth something, though I think those natural wonders mentioned so far are WAY overpowered.
I like the idea of exploring, but % of map revealed and what not is silly, since it's pretty easy to reveal almost the whole map if you set a couple of ships/explorers to auto-explore. Having the explorers hunt for points of interest in a given area seems to me a good idea, but the benefits should be relatively small... small boosts to culture or science or whatever. Otherwise you'd just spam dozens of these things to hunt for really nice wonders.
The big question is whether the benefits should be fat cross or civ-wide. I guess it could vary, but generally speaking it should probably be individual cities. Basically they should act as super-resources, of which there is only one of a given item in the world, and its benefits are unusual and more powerful than a resource.
So it would be kind of like the random event, but souped up and something you could try to "make" happen with an explorer.
Examples from the real world:
Great Barrier Reef - Big boost to science, small boost to commerce.
Mount Everest - Big boost to culture, small boost to commerce.
Natural Harbor of _____ (Rio de Janeiro?) - Big boost to commerce, small boost to culture.
Uluru - Big boost to culture, small boost to happiness.
Niagara Falls - Big boost to happiness, small boost to culture.
Grand Canyon - Big boost to production, small boost to science (I can't really justify that, but some wonder has to get it...).
Tazmania (or Galapagos) - Big boost to science, small boost to culture.
Fjords - Big boost to health, small boost to production.
Y'know what I just thought of that might also be interesting to implement? Drugs... they play a pretty big role in modern life, even on the world stage, but there's no mention of them whatsoever. I guess they'd just be a plague for one civ but a cash bonus to another?