Dutch,
I am really digging the Denali series from Clam this season..Personally, for my ice business I will be putting my clients into the Denali II.. With this shelter they will get the most viable fishing room of any flip over shelter on the market. The seats are comfy and the space is endless.
Now the IV is a good shack too, and has the same characteristics as what I explained above. You will probably love it for you and all your buddies. But, like anything, I would suggest you find a local Gander or Fleet Farm and check them out for yourself. See how much room you all have, etc etc.. Where if it doesnt have "enough" room, you can always look at an X 4 that has a bit more space.
Or, if you plan on coming to the St. Paul Ice Show, stop over at the Clam area and I can help you out as well.
Good luck..