Initially we chose Collett's because it was a bit of a non-choice - you are pretty much the only company offerring catered chalets/hosting etc in the Dolomites. However we've just booked our 4th holiday with you (for Feb 2017)...so I think it's safe to say we choose you because of the amazing service!
It might be nice to have the option of smaller transfer vehicles (even if this is a a slight premium) - I think I'd feel less sick in a minibus than the big coach. It would also be interesting to see if you could arrange for a "ski delivery" service where we prebook skis and boots and they are just delivered to the chalet and adjusted on site (it's offered in a lot of the French alps). One other thing that might be nice (and only necessary in a couple of weeks of the year) would be the ability to ask one of the staff to drop children off/collect children from ski school and bring them back for tea/DVD...the Sella Ronda is so big that getting back for ski school pickup can be difficult! Kronplatz? Perhaps other parts of the Sella Ronda (maybe Canazai?). Also possibly places that are a shorter transfer from the local airports - 3.5 hours is a very long drive. Possibly either the Portes du soleil or the Flaine region would be good for that (look into Samoens).