Hello Lisa:
Well,lately some areas in different sites has been forbitten
to climb by the Federal goverment due vandalism,in the case of
chacchoben ,the kids are allow to climb the big fundations and almost
all of then ,they can do it .in the first one ,we are allow to climb
partially to protect the unopen tumb ,the arqueologist are afraid that
with the weight of the people the weak ceiling may collapse,(make
sense).
They will enjoy it,some of then usually find these small
fruits like coconuts from a a palm,we do not are allow to break then
with any rock from the site .
the place has a nice jungle ,termimates
nest,vines,trees,palms ,bromelias,orchids,some of the plants or leaves
I ll give it to then personally,we offer an interactive tour for then
as long as the parents agree.
The new comers are wellcome ,in fatti ,we can consider a
bus for your own group ,but i do need to know the total numbers in time
to fix the transportation ,also remenber we can depart from the port
itself but this costs 50 usd per person .
or the normal tour by vans from Mahahual or a bus
,depending your group number.
please let me know if you have any other question.
I would expect him to say that all ages will enjoy it but that would be something only you can decide for your kids. Ours will be going at 6 & 8 but they have done 10-12 hour days in DC.
. 
I'm a bit of a worrier when it comes to worst case scenerios so I'd like to know if there's enough time after the end of the tour to give us a cushion if something happens on the way back to the ship. 
You would need to call a company up & ask them about that specifically. Good luck with the GMAT BTW! 
