I have looked into Gamboa Rainforest but never stayed there. Plan do do something on the Panama Canal. I have done the half day tour from Amador to Gamboa. More than long enough. I do plan on doing the full length in either a cruise ship, sailboat or kayak in the future so I was nit worried about doing it on a tour boat.
Lots to do in the city. But depends what you like. A day trip may be nice to break up your week in the rainforest. Or you could spend your first night in the city depending on when your flight gets in. Lots of new hotels have opened up this year.
Car rentals are about $35 a day. The mandatory insurance is what drives up the price. Also driving in panama is not for everyone. It seems very few know traffic laws or common courtesy. This is made even worse by the construction of the metro. Rush hours and lunch time are horrible for traffic. Especially on and just after payday. 15th and 30th of every month. Try to check out Albrook Mall on one of those days especially a Friday night. You will think it is Christmas.
Taxis are a great way to get around but going from Airport to resort then other resort then back to airport would be costly. Ask how much before you get in. They have set prices. Then you can decide if you think its a fair price. They may try to over charge you by a few dollars so if you do not like the price offer less, or try to get another cab. Because of the set pricing depending on where you want to go you will have trouble getting a can to agree to take your fare. About $33 from the airport to the city centre. Decameron has shuttles to the airports for the charters. Not sure if you can get a seat on one.
Public buses are good. But not like mexico ADO's. They can get crowded.
I would never go back to the Decameron. The resort is too big. The staff need to take lessons in customer service. You will fine this all over panama. People are excellent but when it comes to customer service it is the worst. I am not sure what causes such a change in people. The food is below par. The two oversized buffets serve the same food. There are a few a la carte places where reservation fill up quick and then at dinner time they are half empty. I will assume you are trading in through RCI so you will have a special rep and I believe you can eat a la carte every night. Alcohol selection is not great. I do not enjoy drinking beer out of a white plastic cup. Even in college we had solo cups. The water is not clean. I would not put my head under.
From the Decameron, take a day trip up the mountain to El Valle. You will enjoy getting out of the heat for a day, away from the crowds and seeing the ocean view from there. There is hot springs/mud bath, zip lining, hiking, small zoo.
Never been to San Blas but everyone that has likes it. If you take a sailing trip be sure to judge the captain and check out the boat.
There is a lot more to see of Panama then just the resorts.
The country is very safe. Tipping is only at nice restaurants and maybe 5-10%. In a taxi on small fares I'll round up to the nearest dollar unless I need 25 cents to wash my hands or use the bathroom. You may want to carry around a small roll of toilet paper.
It would be good to know some Spanish. Panamanians do not understand maps. Nor are street names and addresses used that often. Better to give directions by using landmarks. Even if the landmark is no longer there.
Enjoy.
