I recently figured out that you CAN tweak Mapquest directions.
Okay, so you enter your direction info and when the listed directions come up, you can go to EACH specific turn/street/route, etc., and click on a button to eliminate that particular turn/street/route and then mapquest will recalculate the directions using an alternative route.
It really is one of the better search engines out there for directions, once you learn how to tweak it to your specific needs.
Hope this helps.