I didn't know Phoenix Comiccon was that big- how does it compare to Comiccon? Last year SDCC was the only con I've ever been to so I think I've got my standards set pretty high....
PHXCC had 80K attendees last year, so it is nearing SDCC size. But it doesn't even come close to SDCC in spectacle, foot print or star power. You may get a few A list actors but not entire panels of them. There are still some great celebrity appearances though, check out the guest list as it gets closer to may.
Also, there are a few offsites, but again it doesn't even compare to SDCC. It's probably more comparable to Wondercon. But make no mistake, it's a big intense con with tons of stuff to do and worth visiting more than one day. This may even be the first year it sells out.
Bummer you can't make it! But you will have some nice plans for 2016!