Hi Greygirl, I am envious, would love to go back to PSV! I think your only issue will be the old 2 man chair to the first run they progress to, that green track. So your 5 year old will have to go with another adult but he/she will have been doing that in the lessons anyway. Then you and your OH can take 1 twin each. I wouldn't take poles either so that you have hands fully free.
I wouldn't bother with the main nursery slope just go straight to the green track. But if you do then you can take the children up by straddling them over your outside leg, this is how to do a drag lift with small child. They put one ski either side of your outer ski i.e. the one at the other side to where you grab the button or rope. They rest against your leg, you put one arm down on them to steady them. It is easier than this sounds!
Can't agree with natation about the ESF though. Why would you go to PSV with Snowbizz and then not use their exclusive classes? Natation I am sure for your kids the ESF has been great but then they are french speakers aren't they? PSV is a very french resort. All Brits there will be with Snowbizz so there will be no english speaking kids in ESF lessons there. The twins might be ok as they will have each other to talk to.
Also Snowbizz is part of the ESI which is well recognised ski school. It is the alternative to the ESF and there are many branches of the ESI in many, many french resorts aswell as a few swiss and others. They have their own easily transferable badge system. Advantages to the ESI is class size, almost always limited to 8 or 10, 6 for the very little ones. Compare that to 23 ESF Oursons in I saw in PSV!!
Re. the ESF in Les Houches, we had a very different experience to Natation and removed our just turned 4 year old. There were only 2 english speaking kids in the jardin with over 20 kids in total. They were shuffling around, getting cold, the other english child was crying, the response from the staff was unkind 'come on, stop that crying, come on, come on, you know how it goes, get on with it'. My husband and I were watching from a distance and my husband who is normally fairly gung ho made the decision to pull our son out even though he wasn't crying but he did look miserable.
Unfortunately in Les Houches there is no other school. I think the ESF in bigger resorts is a different matter as there will be more Brits and other nationalities so more chance or 'international' classes which will be conducted in english. A french speaking class can be a very isolating experience for a young child.