Chip Hitchcock adds several more titles to the list of stories set at sf conventions (see Barf Factor Three, Mr. Sulu):
One of Donna Andrews’s Meg Langslow books, We’ll Always Have Parrots is set entirely at a convention for a TV show with elements of Sheena, Xena. (Her studly ?fiancee? appears on ~half of the episodes, so they’re guests when the unprintable star gets murdered; the title comes from the attempt to reproduce the show’s setting in a very mundane hotel.)
I suppose Murder at the ABA doesn’t really count — even if mundanes would think publishers and authors are plenty weird enough.
And to dig really deep, the end of de Camp’s Goblin Tower is set at a wizards’ assembly that is extensively pastiched from SF conventions, even including an uncredited reference to one of Rotsler’s Rules.
(If you’re curious, Rotsler’s Rules for Masquerades is available here in a PDF file.)