I'll third what everyone has said about the michelin LTX A/T tire. i work in a tire shop where we do a lot of sales of that particular model. My boss actually put a set of 265/75/16's on his chevy 1500 and he loves them. I rode with him and they are very quiet as well as soft. As for tread life, I've seen a set of 245/75/16's on a chevy 2500 in the load range e rating get 80k miles, pretty hard to beat, especially on a work truck, especially for an all terrain tire.
Excellent road "manners", outstanding tread life, and great in the muck. However, when you mention lots of snow and Ice, I'd reccomend my tire over it, Michelin LTX M/S. Much quieter on the road, better handling road, rain and ice. Mud wise, I don't think they'd fare much better then the gy's so it's up to you.
With your 4x4, definately look into the 265 size, I think you'll be pleased. Also, unless you're towing your boat, carrying 2500 lbs in the bed and loading the family up, I'd stay away from the E rated tires, a C rating will do you just fine. for everyday use, 40psi front rear, and fill em up to 50 when you load it up.
Have fun with the choices.