Thanks so much for your advice and suggestions everyone.
Having a think about it, I think the general consensus that we're planning on trying too much is right.
My wife enjoyed the week of skiing she did, but what she is most enthusiastic about is 1. Getting away from the crowds, and 2. Going uphill. I, on the other hand, like to do both of those, but also rather enjoy the downhill part as well! To do this together, we obviously need to ensure that she has the ability to get back down, and so I think some more piste skiing is necessary. We had talked about nordic touring, and while I think that my wife would possibly prefer that at the moment, I worry it would leave be slightly unsatisfied (in fact, I have done it in Canada and it did).
The week's skiing we had last year was in Morzine, and our friend did go off and do a day tour on his own in the Vallee de la Manche. So I think something like that might be one idea. I still very much enjoy working on my technique on the piste, and my wife would be able to do a bit more of that, and we could then get a lesson or two to help us with off-piste. Maybe by the end of the week we could look at doing a half day tour together.
I also take the point about the guide. I've done a little trad climbing, some general summer walking, but I've done nothing in regards to winter walking or mountaineering. Another possibility, which we'd also thought about, would be for us to spend the week that we have on a winter mountaineering course. I'm not all against guides and instruction, in fact I very much value it, and I guess it could be a quicker way to get to the point where I feel more confident myself. What I didn't mention was that our friend has done a lot more mountaineering, although I know he was keen in the past in getting some more professional instruction.
Basically then, the priorities are to A. Start learning the winter skills we need, and B. Ensure that my wife can ski better. After this, my rather romantic original plan might be feasible.
So, I appreciate all the advice that we need to take it a little slower. I'll talk to my wife and see what she thinks. Thanks again everyone.
Post edited at 08:44