Morzine and the surrounding Portes du Soleil area is pretty good for self-guiding, but it’s easy to end up just riding a load of DH tracks because it’s so easy and a lot of fun.
Also as a previous poster mentioned, the lifts don’t open until the end of June.
Have you thought about doing the Passportes du Soleil mass ride? That’s a good way to get familiar with the PdS area – then you could repeat your favourite bits and explore further afield on the subsequent days.
Or another option would be to get a price from a MTB holiday company for a 5-day stay. White Room did this for us this year as part of our road trip and it was a very fair price considering the quality of the riding, food and acomodation.