I don't think an ecotour would be a good kid friendly vacation.

I have a six year old and a four year old and we stayed at Ian Anderson's Caves Branch and then at Thatch Caye Resort and found that both places were excellent for the kids. They really enjoyed the jungle wildlife and although our four year old did not do the cave tubing, he did do a lot of hiking and swimming in the rivers. Out at Thatch Caye we all went snorkelling and the folks out there took such good care of us that it was amazing. They are great with kids and were able to take both kids out to the reef and get them into the water in a shallow area filled with fish and pretty corals. They kept the kids off of the corals and were able to show them great underwater scenery. Their resort runs off of solar and wind power, so it is very eco-conscious. They told us that they also did Mayan ruin tours from their resort, but we didn't stay long enough to do any.

there is alot place you stay some want you stay 4 days or more but go all the country by stay one or two places in belize. i can help you find at chamz78@ymail.com