My husband and I brought our 5-yr old twin daughters (and were also joined by my father and his wife) on Royal Caribbean's 7 day cruise from Panama City, and loved it! None of us speak Spanish well, but that was never a problem.
We spent our first night at Gamboa Rainforest Resort, and if I had a chance to do the trip over I would have arranged it:
A) so we could spend more time there and participate in some of the services they offer (butterfly observatory, guided nature hike, etc)