First and foremost, something that can take wind. Next consideration, space (for lo-o-ng periods when the winds force you to stay put). Lastly, weight and cost.
The Trango 2For a two-person model, an exceedingly safe choice is 鈥檚 Mountain 25 ($500). A classic design聴geodesic geometry with four poles (two more for the vestibule), rugged materials, and roomy enough for you, a mate, and all your gear when you鈥檙e stuck in there for a week. Weight is not bad聴around eight pounds, depending on the number of extra stakes and tie-out lines you take.
This tent has plenty of worthy rivals. 鈥檚 Trango 2 ($550) is the same basic design, with a little higher-end materials (Scandium poles vs. aluminum, for instance). Two person, vestibule at the head end, a bit larger than the Mountain 25. You鈥檒l also do fine with 鈥 Stretch Tiros 2 ($479)聴the same two-person, four-pole design as the others. It works. People don鈥檛 fool with it.
The wild card is a tent such as 鈥檚 Nammatj 2 ($575), a tunnel design that requires staking. But you save weight (it comes in at around six pounds) and of course ANY tent needs to be staked out in high winds. Otherwise these are fabulous tents聴top-end materials, beautifully made, spacious, well-ventilated. I鈥檇 give it very serious consideration.