Carol, it may be that for you taking the bus to the French side is not realistic, but we have been taking buses all over the island for years. We never rent a car and have stayed on both the Dutch and French side. We have travelled by bus to the other side easily and frequently on our trips.
To the OP, it is easy to catch a bus up and down Simpson Bay if you prefer not to walk. My wife and I regularly walk all over Simpson Bay from as far as Lagoonies back to Dinghy Dock. Don't worry, you will not be restricted to 3 bars.
A bus is also an easy way to get to Maho where you will find a nice selection of bars and restaurants, We really enjoy The Hole in the Wall if you want a night of live music. Driftwood is in the Maho area as well (mentioned by another).
You can also catch a bus to Philipsburg. Lots of bars and restaurants to choose from there. We like Grumpy's bar.
To get to the French side take the bus to Philipsburg and get off at the roundabout at the end of Welfare road, walk to the other side of the roundabout (Union Road) and wait for a bus that will take you to Marigot. Lots of places there to explore. Or you can change buses there and go to Grand Case and/or Orient. We have always found the bus drivers to be helpful. Let them know where you wat to go and they will tell you where to get off, etc. Other passengers are also helpful. We find the bus is a great way to experience the island and enjoy the people who live there.
.
