Road Runner Sports has a shoe trial deal if you are a Run America member:


Our Guarantee
Run America Club members 100% Satisfaction Guarantee: With our unrivaled 45-day, Pain-free running shoe guarantee, you have 45-days to try out your new gear and return an item for any reason. We'll refund the full purchase price. No questions asked.

It's worth the cost of membership (plus you get free shipping and 5-10% off everything depending on which level you join) while you are figuring out which shoes you like...

They also have a shoe decision-making tool called Shoe Dog which is pretty neat.

http://www.roadrunnersports.com

Nanci