as far as adventurous on the caves, I recommend cave hiking vs. tubing for adventure. AMAZING experience, incredible. ATM caves.

I recommend staying in San Ignacio 3 nights since you have the time, do that tour from there and it is MUCH cheaper and less than half the time to get to it.

You can do the Tikal tour with any hotel in San Ignacio quite cheap and it is only about an hour from there. Easy to do in a day and they bring you back.

Zip lining is a Jaguar Paw, again close to San Ignacio.

I think you definately should stay 3 nights in San Ignacio or Mt. Pine Ridge area since you have the time. It is beautiful.