Welcome to FlyerTalk!
My recommendation is to view the existing thread we have on this topic, which may also be found in the Forum FAQ:
Everything You Wanted to Know on Where to Sit on the CRJ-700
http://www.flyertalk.com/forum/showthread.php?t=318189
Please use this thread for any follow up questions as well; in the interests of condolidating the information, I'm going to close this thread now.
Please enjoy your use of FlyerTalk and feel free to contact any of the volunteer moderators if you have any questions.
Regards,
FlyinHawaiian, Co-Moderator
United Mileage Plus Forum