Originally Posted by SometimesFlyer

Hmm, here's another angle. I think the train ride in itself may be quite an experience for your kids. If you get the vistadome train, the views are pretty cool. Along the way, it travels along a river valley and you get great views. It can also get a little touristy and on a trip last year, there was a little "fashion show" put on by the crew as part of a merchandising exercise. On top of that, its a pretty comfortable ride. I miss the old days of train travel ...

In the sacred valley, I think the salt ponds and the Inca amphitheater will rank #1 and #2 for your kids in terms of educational and getting their interest. Both of them can be part of a day trip you do out of Tambo del Inka.

The Tambo del Inka is one of my all time favorite hotel so I'm a little biased. I would still recommend staying there as a base, and just doing the day trip to MP and back. Long day, but doable. I think you will find that even if you stay in AC, given the need to go back/forth to Cusco/Sacred valley, your net "exploring" time in MP and sacred valley will be the same.

Have a good trip.