My answer boils down to: I'm looking for a high-level individual contributor (i.e.: not management) software engineer/architect position, a team who gives a damn, interesting problem to work on, and to be working in a language I want to be (Python in specific but I'd consider others: Ruby, maybe Rust come to mind quickly. I'd generally avoid Java/JavaScript/C/C++. I would not do Perl or ops or dev-ops.). Oh and I don't want to move or travel constantly, so either you're where I am or I am working remotely for you.
FWIW, I'll be 39 in a few days, and I spent some time getting a masters. From that perspective, you should probably have the answer to this question down. This is my 3rd job post-school: BS, MS in CS, 7 years working for a public university as a sysadmin, 5 years as a developer for an internet company, and now 1 year at a startup. I expect if I get to 5 years at the startup I'll probably be looking to FIRE not for another job.
If those tenures seem long, its because us midwesterners don't job-hop like the bay area/silicon valley does.