I stayed at the 5 Sisters Resort back in May, and went to Tikal and barton Creek.
I have done a lot of spelunkering-type caves so Barton Creek was a disappointment to me, but if this is new to you it is probably fun - you ride boats in. When I was there the water level was high and some low hanging stalagtites prevented us from going back to the normal tour (1 mile I think).
There is a new cave new San Ignacio that is a bit wilder. Check with your resort guide about booking this. Was in this past months National Geographic's Magazine - Not the normal mag, but some specialized one, I can't remember which publication of NG it was but I have it at home.
Yes there is a beetle problem there, nothing to disturb you, but many of the trees have been destroyed and cut down to stem the problem.