"The smaller cities can't support an 8-show engagement in terms of ticket sales and so the show plays for as long as it is cost effective - sometimes only for a night."
While that is mainly true, it's more of a matter of the theatre goers than it is a matter of the city's size. The city I live in is the same population size as Greenville, SC... but the quality of shows and the lengths of runs that Greenville gets are a lot higher than where I live. Greenville gets equity tours, some of which first run tours, that sit down for 8 shows. Even though it is not a hugely populated city, their theatre goers are active enough to pave the way for better shows to stop through town. Where I live, which is about as populated, we can barely fill out a 2 night run of "The Wizard of Oz".
"There's nothing good on. The media hates Christmas. The media loves vampires, though. Maybe they will show a Twilight Christmas."
-Danmeg's 10 year old son.