Just closing the loop on this one, we had a great trip to Aviemore and managed to do loads
As Scotroutes suggested (thanks Colin), we did Meall a Bhuachaille clockwise from the Glenmore visitors centre, definitely a better way to do it than the normally suggested anti clockwise route (which most people seemed to be doing)
The kids did great, and at 5 and 6 were the youngest ones up there by quite some way (based on the others I saw doing it). It was snowing gently on the way up but a full wind blown blizzard at the top and pretty interesting, I was the only one enjoying it at that point. Slightly slippery but not unsafe, and it rapidly improved once we got off the top. I could see the snow had mostly melted in the couple of days running up to when we did it (I was around the Northern Corries) but I was surprised by how much had been put down in only a few hours, if it had continued like that the afternoon trips would have been much more slippery. Bothy stop was well timed for lunch too, the wind was pretty ferocious and we dodged a fairly heft snow shower.