I'd been through the Panama Canal twice while in the US Navy so it wasn't new to me but very interesting for my wife. The new locks for the bigger ships should be really interesting to see when it is completed.
We found out you could hop on a bus for $4 to get to the beach rather than pay $12 for a cab.
When we were in there previously we had done Stingray City which we had booked privately. I'd highly recommend it.
From there we went to the Veragua Rainforest and did the aerial tram - the road is pretty rough and bumpy but enjoyed this part of the tour and fortunately it didn't rain in the rain forest that day. The exhibits there were pretty interesting. After the rain forest we went to lunch not sure where but the food was good and the beer cold.
After lunch we went to do a zip line, I think it was Las Brisas since we didn't end at a beach and they drove us up to the first platform with a tractor. It was toward late afternoon and there were only five of us from the ship and the two zip line guides. The others on the tour, including my wife, went to see a banana plantation while we zip lined. My wife said the banana plantation was pretty interesting in what goes into really processing bananas prior to being shipped out. I really enjoyed the zip line, hadn't done it previously and definitely would do it again.