Sorry, I can't resistSkigrl:
Sorry, I can't pass on the opening. Wider or narrower waists are only noticed by shallower guys who primarily judge their "skis" by the outside looks and not the more important inner "ski".
Seriously, on a relatively narrow ski, the foot is closer to the edge of the ski and the ski will respond to less pressure. On a wider ski, the foot is farther from the edge and takes a little more effort to tip. This causes the ski to come up on edge a little more slowly and to return to flat more quickly and easily.
While this doesn't affect all of these really good skiers that reside here, the wider ski feel can be very reassuring to more intermediate level skiers. Newer skiers will usually feel like a narrower ski is a little twitchy while a wider ski will feel more stable or will track straight better. The reality is that this is because the newer skier usually struggles a little bit with balance and the narrow ski will respond to these smal variations in balance and begin to turn "on its own".
Therefore, a ski in the range of 68-74 mm in waist width may be better for a newer skier. Also, widths have been going up recently as materials allow a wider ski to not twist (when it bends). 5 years ago a 70mm waisted ski was called a mid-fat and was considered a versatile all-mountain ski, I would say that classification would now apply to 74-76 mm skis. I know, probably more than you really wanted to hear.
Since I like Head skis, I would suggest the XRC 1100 or 800, 163 cm length. But I also like the idea suggested by someone else. Give him a home-made gift certificate good for the ski of his choice or something like that.
My wife and I agreed that, while well-intentioned, she seldom had the background (she's not a skier) to try to buy ski gear (and computer things) for me. It puts both of us in an awkward position. I have to appreciate the effort while regretting that she spent so much on something that I really don't want.
The other thing is that well-fitted boots are more important than skis, and the people here can certainly point you towards good boot fitters who can then assist "both of you" in selecting an appropriate pair of boots for him.