Given the screeds of highway miles I've gotten on various BFG AT's and AT/KO's, I'd pick those. They should also be a little more "available," and easier to get a "road hazzard" warranty on (and if you don't think road hazzard is worth the four bucks, you've never had to replace one...)
BFG AT's in your size should be on sale at fairly regular intervals, from various sources (like Sears!) for about $80-90 each, make that $90-95 each set up, and maybe $100 each with road hazzard. Very good road manners and performance in the wet or dry, and they'll serve you fairly well just about anywhere (they do load up with mud, but if you're not spending a lot of time in the gooey stuff, carry a bag of clay kitty litter if you think you'll be there - it helps. I've done this - I'll usually have a 10# bag with me when I'm going cross-country anyhow.)
5-90