I don’t know what it’s like where you live, but in Joburg a lot of small to medium geek conventions have something in common – the venue. There’s also some overlap in venues for the two big Gauteng boffer larps (MEAD Legends and Tales of Teana). You could do a lot of work to find a venue that’s uniquely yours, or you could follow the common sense approach.
Hunting for a convention venue
I’ve only done the grand venue safari once, but I learned a lot. Here's some of the kinds of venues I found through Google and why I didn't go with them.