sounds like Performance Based Routing (PfR) might be useful here. Have a look :
Cisco PfR presentation.pdf 1.7 MB
OER/PfR as mentioned is one method.... PBR (Policy-based Routing) is another for certain traffic types going one way over the other...
Or other routing manipulations may be good for you as well, by implementing the IP SLA features and tie them to routing changes (EEM can manipulate the bandwidth or delay values on your interfaces based on reactions which in turn will manipulate routing metrics and therefore routing decisions).
Any path can be arduous and should be looked at in detail on the design vs. business needs basis as you go forward!
But have fun with it!!!