Gambia is as much about its people and their culture as its lovely beaches and scenery. If you spend two weeks on the beach or by the pool you will miss out on so much.
Get out of your hotel and take a look around. You will meet lots of people who want to 'help' you enjoy your stay - probably more than lots! Be polite if you can and take one or two more trustworthy-looking ones up on their offers - you might end up doing something really interesting and memorable. All they will want in return is a good chat and a few Dalais for their time - you may even become good friends. Just don't be stupid and don't do anything you really don't want to do!
The package tours run a number of excursions and these can be a great introduction to the sights and sounds of the real Gambia and, of course, come with a guarantee of safety for the warey traveller.