I think scheduling would be the most important factor. Most other series' have their schedules out -- takes a lot of research. Heads-ups are ok, but I'd travel for the right race regardless, as long as it fit the schedule.
Seems like there's a huge number of S/SS Combo events and series in this region. I'd almost rather they consolidate a couple races here and there and promote to a wider region, if you could get guys to travel for it, and have some larger car count, larger purse races to complement the other smaller, more local races. It takes all kinds!