In reply to jon and simon4:
I know Gross Wannenhorn is a defective mountain, but if you stand on the higher of the two summit rocks and raise your ice axe you can just about make 4k....
The views are as great in summer as in winter. On the way up you can see the sun rise behind Finsteraarhorn, and once on top you have the steep drop down to the Aletsch Glacier, with fantastic views of Konkordiaplatz and Aletschhorn.
With good firn the route is straightforward, the main difficulty being the crossing of Fiescher glacier half a kilometer or so south of everyone else (you can always join the hordes making the crossing towards Gruenhornluecke and then move south, but the main point of going to GWH is to be on your own).
We did GWH after some days of heavy snowfall (plus two days of letting everything set), which meant keeping an eye on the avalanche risk and breaking trail for the entire route, so it felt a bit more wintery than otherwise.
CB