There's one where the people seem sort of... senior - a walking group. They schedule things in the middle of the day when all of us worker bee's are busy. There are a few others that are geared more towards 20's - early 40's. There's usually only about 4 - 6 people at each meetup, although the Food and Wine meets have been getting more. Some people come late (or don't turn up at all), other's leave after a while or go off and do their own thing. You're not locked into anything and if you decide to ditch the group, you'll get nothing but friendly goodbye's from everyone else. I'm a total introvert (it takes me 3-4 days to recover from going to these things; all I want to do after is be by myself), but having just moved here, it's been a nice way to get out and meet people. Some I'm not too keen on, but I've become friendly with a few. And it's not at all cliquish, which is something I was worried about. I thought people would have their buddies within the group but, even though some do, everyone seems to mix things up; like walking to a ride, you end up talking to one or two people, then standing in the line, you might talk to others, then riding the ride, you end up with someone else. Nobody scrambles to take a seat next to someone else or anything. And you don't really know the ages of other people unless they make some obscure pop culture reference. Most of the conversation revolves around Disney parks and movies, which is sort of an ageless thing. I'm just over the tip of 40 and I'm pretty sure that the people I shared a table with for a meal at the last one I went to were probably in their mid-20's, but the three of us were able to keep conversation going the whole time with no problem.
I can completely understand not wanting to do it, it took me a while to give it a try, but it's all people who are into going to the parks and if you want company while doing it, it's probably the easiest place to find it. I'm not preaching it to you, I'm just sort of trying to give an idea what you could probably expect (which might scare you off even more). I still go to the parks by myself more often than not, but when there's something that seems appealing to me and is at a time when I can go, I've gone and I've had a good time.