I recently read an excellent Trip Report on St. Kitts that you might find helpful.
"My husband and I just returned from a week on the incredible island of St. Kitts. St. Kitts is the quiet caribbean of old which has given up the sugar cane industry, two years ago, and is now embrassing tourism as it's financial mainstay. The new Port Zante, built for the cruise ship tourism is almost complete and will house the typical cruise ship terminal stores - it is large, open and appealing. Shopping in Basseterre is quaint and local. There are restaurants and locals selling local cuisine. We visited Romney Manor and bought as much batik as we could carry back on the plane. They gave us a demonstration of the art of batik which was interesting and informative. Brimstone Fort is breathtaking with its views of Saba and St. Eustatius. We took the Sugar Train around the island and were able to see how the old coexists with the new. The singers on the train were remarkable, and the drinks offered, both alcoholic and non, were plentiful. The island, everywhere, was the cleanest island we've been to in the Caribbean (and we've been to over 25 at last count). The pride of the culture is seen everywhere, from their kind nature, warm greetings, helpful attitudes and beautiful country.
Cab fares are set by the government and are reasonable, so please don't insult the local drivers and try and "negotiate" a better price.
We ventured off the Marriott property almost every day and found some delightful local establishments. Among our favorites were Reggae Beach - on the peninsula which has an incredible view of the Sea, fabulous food, great drinks and great people. It's worth the drive.
We ate freshly caught daily caribbean lobster at Mr. X's Shiggidy Shack almost every day and don't miss Thursday night's bonfire and flame eater entertainment.
We took the ferry over to Nevis, the price is minimal but don't forget to go to the second window for the $1.00 port tax, we figured this out when the locals started queing up at the window.
The ferry ride is about 45 minutes but great views of both St Kitts and Nevis on the way. Barry of Barry's Taxi on Nevis was fantastic. He showed us all around the island and is very knowledgeable about the history and local stories of the island. Don't miss Sunshines - home of the Killer Bee. Great food, great service, great swimming location. Definately want to return and stay on Nevis just to spend time at Sunshines as the people there and the locals made you feel so at home and welcome. Nevis reminded us of what St. John was about 10 years ago, so if you have money to invest, this is the place to do it because when St. Kitts is discovered by tourism, Nevis will be discovered as well.
We loved our trip, will definately return again. This is the quiet, laid back Caribbean of old. There is little fancy shopping and few fancy restaurants, (except at the resorts) but if you are looking for a vacation spot that will make you forget about the traffic jams of home, the stress of your job, and the trans fats of fast foods, then this is the place for you. You will be reaquainted with the important things in life - the value of friends, both new and old, the importance of living in the moment and the appreciation of mother nature at her finest- both above the ground and below the sea. We wish you all happy travels and great adventures and boat drinks to all."
We rented a car in Barbados and really enjoyed it.
We rented a moke at Stoute's from a kiosk right at the cruise ship terminal. I think it cost about $90 for the day.
We drove north along the western coastline then cut across the northern tip of the island. We drove south along the Atlantic coast past Bathsheba then cut inland stopping at Gun Hill then back to Bridgetown.
It was really nice being on our own schedule and could stop when and where we wanted. We stopped at the windmill, which was kind of cool. We stopped at St. Nicholas Abbey but it didn't seem worth the time and cost of admission so we passed.
We had very little trouble navigating around the countryside. The roads were pretty well marked and while we made a few wrong turns, we never got hopelessly lost. In town was another matter! There were NO street signs that we could find in Bridgetown. We had to stop 3 or 4 times to get directions back to the ship. We finally spied it across the rooftops and just drove in that general direction.
Agree with other comments, but be careful if you go to Nevis on the local ferry, you could be delayed getting back and miss your cruise ship
Big Banana Bus also does a good tour around the island and can be booked in the ferry port, also good maps of the island can be had from her.