I've got two things I want.
that's basically it :) The last 3 times I was mostly outside talking to other developers not listening to the talks. Come for the talks stay for the people :)
For me, the meetups that have been the most valuable to me have been the kind where there's a small crowd of people (50-150), and either an individual is being interviewed, or there's a panel discussion, followed by a question & answer session where anybody in the audience can have a good opportunity to ask questions to the person or people on stage and have a chance to be pointed in the right direction.
Usually these types of meetups are filled with people covering the whole range of experience, from no experience and just curious, all the way through to professionals working in the field, and having that range of experience leads to easy discussion, and lots of excitement as people begin to understand something new!
I think for me it's all about hanging out with like minded people. While I get to do that at work and on Hashnode, it's really nice to meet the community in person and hear what they've been up-to.
You gain a lot in terms of keeping yourself up to date and making connections.
It usually comes down to: what can I learn tonight?
I mean, usually you can put a meetup talk in one of these three buckets:
The vanity talks are usually nothing more than what you could learn by doing some homeworks: watching some conference recordings, reading some whitepapers... So if you don't have time to do this, and prefer to catch-up later locally with free pizza, then these kinds of talks are nice. If you're quite up-to-date on the subject, then the free pizza is the only thing worth.
All that to say, that all the best meetups I had were when there were a real story about what were the good, and the bad part of adopting/changing this or that. No matter if it's developpement oriented, infrastructure oriented or whatever. Knowing the good parts is easy, usually that's what has the most visibility, so it's easy to learn about it even without meetup.
But meetup are the opportunity to meet and listen to people who tried this before you and hopefully did well, but - as any tech change - faced issues, unexpected problems, and had to solve them. When the present these challenges and how they solved them, that's usually a great meetup, where I learn something I couldn't easily learn on my own, until I face the same issues.