i'm currently leveling a warrior too and looking for some kind of tanky dungeon master that will be doing lots of dungeon spams but can also solo quest time to time. i've only leveled warrior beyond 30 in cata+
i'm getting mixed answers from my guildies who have leveled warriors while doing dungeon grinding. some are saying full arms is fine to 60 or 55ish. others say level arms w/ 15 points in prot, others say 13 arms then go into prot.
i can't imagine full prot is very good. viable, sure, but if you quest it'll likely be too grindy and do no dmg. so waiting for input as well

but if you aren't planning on doing very many dungeons, there's absolutely no reason to level as prot unless you're just a masochist