Well, I reside both in southern CA as well as the SLC area of UT. I am leaning toward UT, as I have a few friends that would like to come and I know of many cheap/free areas and have connections there to make it a bit better and easier for people (and cheaper for me to support the con), as well as know the area well enough that we will not have to search for anything, really. Also, out of the people mentioned thus far, it is a relatively "center" location to have it. Those Michigan folk drive the point much further, but I don't know of anyone in those states.
Feel free to give input on this ;)
