Well, my fret wire is on order from Gitty. My plan is to cut the slots, finish the neck then fret it. That way I avoid getting finish on the frets. Anyhow, when building other projects I've always used Poly. It works good for most of the things I've built. But I've never built a guitar. And since I don't play a guitar, I don't know what a good finish for a neck is. I assume you want it to be nice and smooth so your fingers will slide. But also durable so it's not coming off in sheets while you play.
So what do you experts like to put on you guitar necks to make them nice but also works well for playing?