You could go with a dome, tunnel or perhaps even a mid/tipi…even with a stove if you like.
I like the Hilleberg Kerlon fabric, because snow slides off it so easily. Snow doesn’t seem to slide off as easily on the PU coated fabrics. (The silnylon on the Big Sky Tents is slippery as well…I think most silnylons are this way). Regarding the Hilleberg domes, I really like the massive roof vents…if you keep them open they do a great job of keeping condensation down. You can can reach right through the inner with the vents open and tap the fly and the snow just slides down the sides of the tent. You don’t really need to go outside to clear off the tent. And you can keep the vents open in most rain/snow conditions because there is a separate vent fly that covers them.
Regarding the Allak, you and your wife could fit in there if you are both using 20 inch wide pads and 6-0 sleeping bags/quilts would be preferable. I’m not sure how two 25 inch pads would fit. The Allak also tapers in width toward the foot end.
Tunnels are cool…they do the best job with weight/space. I have to admit that Macpac Olympus looks great, especially the sod flaps on the vestibule. The Hilleberg Tunnels will give you more room at the head and foot for the most part in comparison to the Hilleberg Domes (The Nammatj and the Nallo slope at the foot end, while the Kaitum and the Keron do not).
I would check out some of the Terra Nova tents as well…I think their fly material is some sort of silicone coated nylon, which I do like for snow conditions.
The Mids and Tipis are generally floorless, and you could get a pretty big mid or Tipi and still be lighter than a tunnel or dome. However, in big snow they snow load around the bottom outside perimeter so you will have to clear that off. And you’d have to determine if you are comfortable with floorless or not.