I have personally only been to Armadillo Con in Austin, TX.

http://www.armadillocon.org/writers/index.htm

It is mostly for writers, not readers.

In Phoenix we have LepraCon in the spring and CopperCon in the fall .One is supposed to have an S-F arts focus and the other literature but the main draw to both is usually an author .We've also hosted WesterCons which is a regional S-F gathering .I've met Larry Niven , Spider Robinson , Marv Wolfman , Alan Dean Foster, and many more .These days I can only afford one Con a year so I usually do a game convention . Reader's/Writer's cons , what I call general cons are really my favorite as they are the most relaxed for discussion and meeting people . They often include events featured from other types of cons .