Honestly, I haven't really got as far as a license for the code yet - I don't know much about them, and people seem to have strong opinions about the standard options for OSS.

I'd be interested in what folks recommend for something like this, and what the trade-offs are. Seems like MIT is the go-to in many cases?

EDIT: Done, on GPLv3!

GPLv3+ gives you the most options. You can always relax it later if needed (easy to do as long as you are the sole copyright holder).