I don't work with maps often (though I know posters pretty well) and I've certainly never valued them. I'd assume you'd look for the practical things in paper: a low amount of rips, a low amount of color fading, and a low amount of water damage, stains, etc. It is not practical to frame anything in an archives, though you can frame if you'd like. Outside of framing, they should be stored flat and unrolled, usually foldered in a map case, though if it's your personal collection that's a bit silly. A box like this with foldering would be good.

I'd disagree with the poster in the other thread, you can do a few of your own repairs if you know the basics of conservation, it's not terribly valuable, and you're not just gluing and Scotch-taping like a crazy person. I have had maybe 3 hours paper conservation training and I make minor repairs regularly. Small and uncomplicated rips on normal paper can be repaired easily with Filmoplast tape. It is easy to use and reversible. Basic how-to. If a map has more damage than that and you really want it, paper conservation on a large and complicated piece like a map is maybe $200-500, depending on how crappy it is. Roll of Filmoplast is looking pretty good right now, right?

If your map is valuable, the UV framing glass is not bulletproof against UV light, don't rely on it to protect your paper. However there's no point in collecting things if you aren't going to enjoy them. I have a couple of meh-valuable prints and I just hang them away from windows and light.