Hi! We also skied the expansive Portes du Soleil area. We were based on the French side (at les Prodains at the foot of Avoriaz), but we skied to the Swiss resorts a couple of times. I think Portes du Soleil have to be one of the closest resorts to Geneva, I think they are located 1.5 hours from GVA.
Regarding the skiing, I will let my husband respond to that...
Morzine and Les Gets are nice areas with much intermediate terrain, good lift access and plenty of places to eat. Unfortunately, they are fairly low. I believe Morzine is at 900-1000 metres at the base. Just up the road is Avoriaz where the base at Les Prodains is 1300m and the base of Avoriaz village is 1800. My recommendation would be to drive past Morzine and up to Les Prodains parking lot, buy tickets there and take the telecabine up to Avoriaz. Another great place to park would be in Ardant at the base of Avoriaz.
At any rate skiing in Avoriaz is pretty fun, and even when busy, you should be able to find some pretty desolate areas. In particular at the top there are several sections called "snowcross". This is the in bounds version of off-piste and I was able to find ample powder in there 2 weeks after a storm. A little ways down, on the trail leading to the area called Ardent there is a tree lined section that gives way to some excellent tree skiing. Finally, if all those runs are crowded, I recommend going to the top of Avoriaz (2400m), the skiing down the runs going down the left hand side of the mountain as these will lead to some nearly abandoned advanced slopes that take you down to Les Prodains.
We did also ski over to Champoussin/Chambery which is very easy to get to from Avoriaz (basically the back side of the mountain) but it is south facing, so if the snow is thin it may be a little bare.
Hope this helps.