I've driven the Lyon to Moutiers stretch enough times to know that you want to do it at an obscure time of day if at all possible due to volume of traffic. I spent 2 seasons in Les Trois Vallees before coming to Canada plus many trips to other neighbouring ski resorts.
It is not unusual for the transfer from Lyon Satolas airport (that's the main international airport) to Les Trois Vallees to take up to 6hrs (in fact I've had worse than this before in either direction) ... I know they normally quote 90mins - 2hrs but I have never managed to do it this quick other than at night ... although the suicidal French taxi driver is another matter (and another story)!! Anyways, if you hit the roads at a bad time ie. a major holiday ... well put it this way, the main part of the trip as far as Moutiers is the same route that those going to Les Arcs, Val D'Isere, Tignes plus a few other big French resorts will be taking.
On the occasions I flew I went via Lyon (due to price / availability) but I think if I were doing it again I would go via Geneva & take the train to Moutiers (which is at the base of the mountain road up to the various 3 Valleys resort villages) ... others who have done this have told me that it actually works out quicker because it is easier to get the train from Geneva airport.
If you go here (http://www.merinet.com/
) they have links for shuttles to/from both Geneva & Lyon to all of the 3 valleys (plus other resorts). At least this way you can travel in a bit more comfort than the regular bus.
On my last season there I spent half in Meribel and half in Les Menuires ... we stayed near the bottom of Les Menuires (both geographically and in terms of the smell which welcomed us from the near by sewers). This is also where most of the Dutch stay (sorry any Dutch folks, but you do seem to go for the cheapest option & the uglier the accomodation the better). The higher parts of Les Menuires have much nicer accomodation.
Les Menuires is where a lot of the French also stay when holidaying there ... and they don't seem to go out much so the nightlife is very quiet in comparison to Meribel which is dominated by Brits (depending on youir perspective that's not necessarily a bad thing).
There are actually 4 valleys and you can ski all of them in one day ... although at a bit of a push. It's an expensive taxi ride if you end up in the wrong valley after the connecting lifts close ... Meribel to Les menuires, for example, takes about 90mins in the winter!!
Les Menuiries is well situated in terms of being fairly central for the whole Les Trois Vallees ... better than La Praz or La Tania for example where you are very much over on one side of the skiable area. One of my favourite parts of Les Menuires is an area known as La Masse ... there is some excellent off-piste including a massive powder field that you see facing you as you decend in to Les Menuires from the Meribel side.
If you want more charm and a small French village with a direct chair lift access to the rest of the resort, then St. Martin de Belleville is very nice ... and has probably my favourite night spot in the whole 3 Valleys (Brewskies). The run home is a great one to finish the day on ... not too challenging other than the length. There are some very nice chalets here.http://www.st-martin-belleville.com/en/index.php
If you wish to avoid the crowds (on the slopes) then any of the runs decending down in to Mottaret get very busy at the end of the day and pretty icey as a result. Courchevel 1650 tends not to get too busy and there are a nice mix of runs there ... as well as a couple of long poma lifts (just to be warey of if you have any boarders with you).
I could go on forever about the place as it's probably my favourite resort in the Alps ... anyways, enjoy!!