i think this is a very hard question. in one hand you need those "big " markets so you can bring in the needed sponsorship along with a possiblity of having games on tv ( i would assume thats usarl's ultimate goal) but at the same time a vast majority of the Big markets are so saturated with sports options for the fans that you set up clubs in those markets to essentially fail, granted there are some sports teams in nitch sports that are established but that doesnt mean it will always work. now with small markets you have a bigger chance of having clubs succeed because there are less options for fans to choose from in stead of rugby league. but again if you have the league playing in locations that barely have 200k then its going to be a up hill battle.
now the usarl has clubs in the right market to get the ball rolling, what i would like to see is to look at smaller/mid markets moving forward. raleigh north Carolina, Charleston west Virgina.