The selection of CLT is good since it does not require a 757, whereas PHL or PHX would. The assumption has to be that US can provide adequate yields on the route with primarily connecting traffic and cargo revenue - the better possiblity, since it's unlikely that CLT business interests and local tourist traffic alone could produce acceptable results. Personally, I see the route as a waste of resources to a destination with potentially limited appeal from US's general service areas. Now if it was from the now defunct FLL hub, that would be a whole different matter. IMO, a (re)start of PHL-MEX with a 32x would have been a better use of current resources. I'd assume Parker, etal, have some insight into the route viability and aren't making this decision based on ongoing DL fever (ATL-BOG).