Some time ago, I caught wind of an idea I really liked: instead of our next space destination being the Moon (again) or Mars, we should go to a near-Earth asteroid.
I loved this idea. It has a lot of merit: a lot of these rocks pass us at relatively low speeds, making them easier to get to in terms of time and fuel. We know very little about them, and a manned mission will teach us a lot about them (as well as how to do long-term missions like this). And given that these objects can be a real threat, the more we know, the better.
I was interviewed about this briefly for an article in the Houston Chronicle where I give this opinion. The article has some interesting info about a potential asteroid mission, and I really do think this is a good idea... except for one thing. I want to see us planning for and executing a mission to an asteroid at the same time as we do the same thing to return to the Moon, and keeping our eyes on an eventual mission to Mars.
All these worlds really are ours. We just need the will to go and explore them.