what kind of advice are you looking for here exactly? like i don't think much needs to be said regarding layout - you know it's best to keep it simple. the most dangerous idea you stated is the meetup idea. people will meet up on their own, but when you design your site with that as an intended result you have to beware of 2 things:
1) the dangers of promoting such a thing
2) the fact that it will unquestionably be used for sex.
the first one will get some issues with minors more than anything else.
the second will kill a lot of what you seem to be aiming for. even if it can be a success it's not what you want your site to be known for.
if both happen, that's the worst case scenario and what you want to make sure you get no heat for it.
so here's the deal, you want local meetings and stuff? fine. start with the basics. you'll need 2 main boards for this:
1) something like a Social Events board. this mostly goes for larger groups, or rather events where larger groups/more risk will be met. meet ups won't be randomly generated by nature, but there will be something that people can go to and meet up there, as a group. this is something that's actually pretty necessary for a lot of people since they hate going to events solo, or need other people to go with (e.g., staying at a hotel for a con). you can help satisfy the con go-ers by giving them a place where they can stay with other people at a hotel. just remember the 1st problem and how that can affect your site; having some sort of feedback system in those instances can be a good thing as a pre-caution.
2) a suggestions board of a large event. eventually you can expect the idea of having 'social get-togethers' come up if you get big enough, and at that point you can cross that bridge to how you want to tackle it. but by then you'll have already established a particular community and should know much, much better in what drection you want to go.
for smaller-get togethers, it's too much of a hassle to go through all that. big events need organization, little ones don't. like if someone wants to go to Raw or something with others, no need for that. but try to keep the get-together rules more focused on events than anything else. shows, concerts, parties - you'll have to decide how far all that's fine to do. you can even try for a sort of board for young adults, where you can try to split some people for both job hunters and alcohol. any meet up there would be assumed (or rather, stated that those who participate ought to be) adults, so the biggest problem of minors wouldn't be as much a concern.
you'll need people from a lot more than just board 8. board 8 can get you some people from major cities if you want, but we're too small for that idea. at best i can think of is using facebook to try to get some people in? but for that you'll first need to have a catchy site layout. if the first apperance sucks, you'll never get anywhere. at the same time, you do need a base to work with as if people just see a blank site they won't be interested. so you do need some people to make it interesting before you really start expanding as people go 'hey that looks fun, i wanna go there too.'
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The future must protect the clone's past.
"Maybe it's a tentacle, molesting the planet itself. - Aschen Brodel.