CLT seems to really struggle with secondary destinations West of the Rockies.
US/AA tried CLT-TUS twice, once immediately after the HP merger, which lasted roughly a year or so. They brought it back again last year and it lasted a similar duration. Loads were great IIRC, but I think yields were terrible and I'm sure AA is just as happy connecting the traffic flows from TUS over PHX/ORD/DFW.
CLT-ABQ was also tried last year and was supposed to be a seasonal flight, but only lasted one season.
CLT-SJC seems like it would make sense, and lasted two seasons. As someone said above, the second year of the flight the season was longer, and I really thought the flight was going to go year-round, but then AA announced the route was going to be suspended.
CLT-SNA would make sense, and IIRC a couple of years back (around 2012 or so) I heard rumors that US had apparently secured slots for SNA-PHL/CLT and even had a preliminary schedule for the service (both were to use 757s) but nothing ever came of it.
US used to do CLT-EGE with a 757 but it was suspended around 2007/2008 IIRC. They are bringing PHL-EGE back this winter. AA launched CLT-MTJ I think two years ago, but I don't see it loaded in the schedule this coming winter.
The only successful Western-routes launched in the relatively recent past would be SLC/PDX/SMF, all of which fluctuate between once and twice daily flights at different times of the year.
If SJC/ABQ/TUS can't work, ELP/BUR/FAT/ONT are certainly not working.
RJ85, F70, E135, E140, E145, E70, E75, E90, CR2, CR7, CR9, 717, 732, 733, 734, 735, 73G, 738, 739, 744ER, 752, 753, 762, 772, 77E, 77W, 789, 319, 320, 321, 332, 333, 343, 359, 388