IWA makes Flyertalk.
I've kicked around thoughts on IWA for a while during my day job, which is very closely related. Bellingham and Gary/Chicago have had service until as recently as a few months ago when the carrier shut down. I want to say the only current service is the North Las Vegas flight, which isn't even daily.
Allegiant has been around for a while, so I'll see how their flights go. I honestly would prefer commuter feed into a hub (UAX to DEN/LAX, US to LAS, DL to SLC)------- all of those would have potential for a significant amount of local traffic. If places like Imperial and Yuma can support a commuter flight or two to LA, I'm sure Williams can, with its free (is it still) parking, proximity to the 202, and the crazy growth in Queen Creek.
But, given the point to point nature of Allegiant, I'd say that Chicagoland (with RFD being hungry for service) and SEAish do make sense. MSP would be my next target for the snowbird set. Frankly, there woujld be latent demand from a number of chilly midwestern spots like MKE or DTW. Dreaming a little, how about seasonal charter-type operations to/from Western Canada, a la Orlando/Sanford?