You've got some options being in the area, as the others have suggested.
KW in Waterloo - team practice/tournaments.
Adventure Park in Shellsburg -great for open/rec play, not sure if they do team practice there any more though. I may be wrong.
Velocity Paintball in West Liberty - My home field. Great for open play / beginner paintball. You will not find a tourney-level paintball experience at Velocity. Fun if you're looking for relaxed, open games.
ICU in Des Moines - good sized indoor field. Usually plenty of people to play with.
Archery in Altoona - Becci gave you all the info there.
Best Shot in Dubuque - never been. But heard good things about the field.
MVP just across river in Illinois - http://www.mvpaintball.com/
I think that's about it within 2-hr of drive time for your area. I apologize if I missed some.