Any Planet/Moon that could create a winter sort of icy cold feel! With vast overshadowing snowy mountain lines and massive frozen oceans and lakes. It could be a great setting for the introduction of a new race, be it friend or foe! I think a more primal tribal race would be really cool, sort of like a winter version of "Tusken Raiders" where they are not necessarily evil or out for intergalactic domination but more of a hostile thorn in your side if your cross their paths and could possibly ambush you! Being able to play in underneath the great frozen oceans in forgotten mega cities could be insane as well! The possibilities are endless...