Thank you all very much for the input; lots to think about indeed!

The problem I have with flying is that the kids want to see everything they missed out on last year (predominantly Death Valley & Grand Canyon) and this kinda got tacked on to the idea of the Colorado trip with the knowledge that this is likely to be the last time we take this sort of holiday due to a) the insane cost of flights and accommodation these days and b) they are getting to the age that they will want to do their own thing rather than going on holiday with us.

Originally the idea was to fly to Vegas, spend a day or so with Kristina's family settling in and then drive to Death Valley before backtracking and proceeding on with the trip largely 'as is'. We allowed 3 weeks for this but, when it came down to booking flights, it was actually cheaper to extend the trip by another 3 days and fly out/back to/from differing airports. With this in mind - right or wrong - we extended the trip to what we have now.

I will certainly look at things again and talk it through with everyone but I suspect that it will be hard to persuade them to drop their expectations of what they want to see so I expect to retain a relatively fast-paced trip of some sort coupled with a good percentage of stays being for multiple nights and, additionally, the option to skip certain destinations or re-route as necessary if and when people become tired and need to slow down.

I understand about the climate however, sadly, without incurring the wrath of the local education authority, I am limited to those dates so I have to mitigate the situation as much as possible and I am under strict instruction to ensure that those stops have a pool wherever it is possible for them to do so. Obviously not always possible (eg Grand Canyon unless staying outside the park) but these things certainly make a difference in the summer months.

As I say, definitely a lot to think about and we will talk it all through again for certain. I suspect that, if anything goes, it will be the places that I would like to visit rather than the places the kids want to see and that is as it should be as this is supposed to be for them whilst our reward comes watching them (hopefully) enjoy the new sights and experiences around them.