This cannot be emphasized enough, so let's get this out in the very beginning. Even before you start to look for venue, or have an expectation of what your GGJ site is going to be, we just want you know that GGJ has never turn down site applications solely because of low capacity, low budget, or venues where jammers can't stay overnight on-site. A small school classroom with 12 folks jamming together that has minimal promotion, is as legitimate as a corporate-sponsored, well-promoted 250 person site using a ballroom.
Besides primary restrictions like the size of the venue and budget, how big of an audience can you reasonably reach either online or offline?
Maybe you are taking a game-making course at university, then your coursemates can be easily reached. Or, if you are attending a regular meetup around games, but don't have local game jam presence yet, then maybe the meetup attendees will be interested in starting a local GGJ site.
Again, we very rarely turn down applications because they are too small - as long as you are filling a space which is not yet covered by GGJ (be it geographical or cultural) and your site is open to the public, then you are in with a really good chance of getting approved.
Don't overwhelm yourself with unreasonably high expectation for your first GGJ site. Start small and grow from there.