Camping/Beach/Outdoor Gear: One of the most important things to bring with you if you are travelling with small children to Mesa Verde National Park is your baby backpack. Several of the trails would be impossible to take if you do not have one of these. It really allowed us to go everywhere we wanted to go quickly and efficiently.
Toiletries and Medical Supplies:
Sunscreen is really important so you don't look like a boiled lobster at the end of the day!
A bottle of Purell or baby wipes is also a really good idea. The toilets can be a little nasty.
Photo Equipment: Have something with a zoom lense. You can see a lot of the ruins from overlooks. If you don't have a camera or video camera with a great zoom lense what's the point?
Miscellaneous: LOTS of water!
Luggage and bags:
If you take you cameras, photocameras, binoculars or other equipment, make sure you have strong straps on them. A ranger told me a story about video camera fallen to the canyon. it was retreated by rangers next day, but I guess never returned to the owner, or, perhaps, it was not in working condition anymore.
Clothing/Shoes/Weather Gear: Hiking boots or something that won't slip from your feet. You will walk a lot, and you will climb ladders in ranger-guided tours, so it is better to feel safe about your shoes.
Photo Equipment: telelens and binocular will be great in the park. many dwellings are far away from overlooks and it is almost impossible sometimes to see dwellings without such equipment.
Clothing/Shoes/Weather Gear: good hiking shoes are "must-have"; to get to some of the dwelling you'll have to climb up ladders and stone steps