Yes for pure science. I am all for spending on science and I just think private industry could do a better job of getting us to Mars and back if there was competition for a congressional prize.
I am all for a moonbase too. If we can have scientific camps in the Antartic we can have them on the moon too. My palmpilot has more calculating power than the computers that Apollo used so the Moon is way do-able.
Actually, the asteroids are easier/cheaper to reach than Mars. Asteroid missions would ramp up science also. The main advantage to the asteroids is that there is an entire planetary mass worth of pre mined contsruction material that is already in free fall.
If you imagine that humans have a spacefaring future, the asteroid belt is the logical means toward that end. Any Mars mission would just be a diversion.