Any KnitPicks yarn. High quality, low cost wool. And, you might want to consider getting a copy of [I]The Sweater Workshop[/I] by Jacqueline Fee. Then you will be able to calculate your own sweaters, knit in the round, at your own gauge, with your own yarn. You don’t have to follow a line by line pattern. Plus, your Options set will get you through most of the sweater knitting, but you will need a large selection of DPN’s and 16" circulars (all available from KnitPicks, so you only have to order from one company, and you will most likely get free shipping.)
I also highly recommend knitting all your sweaters in the round, from the bottom up. (it’s what I do all of the time) for several reasons: You can try it on as you go, there are no seams to sew up (a big plus for me), and they always seem to get done faster.
As for yarn fiber, since you’re on the road a lot, I would recommend a superwash wool, because you can just throw it in the laundry with all of your other stuff. You can wash acrylic, also, but if you can get a high quality wool for the same price as a synthetic, why not?
Hope that helps you out!