I don't know first hand but I guy in my class at XJT commuted from SLC for about a 6 months... gave up and moved to Lake Charles ( I never quite understood why)... He did say to could get pretty tough.
The few times I have done the IAH-SLC trip in an XR and they have always been full with an ungodly amount of bags... like in the 70's. One leg we couldnt get the jumpseater on... (wasnt even close) normally I do what I can for the jumpers but we were filled to the gills.
Delta might do you better but I can't really speak of them from any personal expriance, but they do run MD-90s to IAH that might do OK with wieght issues...
I would not try CLE you would have to 2 leg that one, and EWR is probably a challange as well.