Kuressaare
Kuressaare is the main town on the island of Saaremaa. The town itself has a recorded history back to 1381. Today it's a pleasant small town with a lovely market, some interesting restaurants, and a small beach. It's a great base for exploring the island of Saaremaa. The town also has a small beach, a nice castle with a moat, and a quaint residential area. You can easily reach the town by bus from Tallin, but once you're on the island there has very limited public transportation. You really need access to your own car if you're hoping to explore the whole island. There are a couple of small places you can rent cars from. All cars are manual so it is important you be comfortable driving a manual car.
Saaremaa has remained rural and frozen in time due to its isolated location, particular during Soviet occupation when it was used as a military base. The island still has working windmills, hand placed stone walls, and old stone churches that feel like you've stepped back in time. There's an outdoor market in the center of Saaremaa that is a great place to try some homemade specialties, especially the homemade smoked salmon. There are also a handful of restaurants around town that serve up some great meals.
Most people travel to Kuressaare during the peak summer months when the weather is at its warmest. If you're going to be visiting town during this time it is best to have reservations. Earlier or later in the season when the weather is not always ideal you will find the crowds less and the prices generally lower. Some places may not be open as well however. Many local residents have rooms available for rent and if the tourist crowds are not high you can easily negotiate a very cheap price. Most rooms come with a sauna, making for a very relaxing vacation. Many also have their own kitchen so you can head to the market and pick up some fresh seafood and then prepare your own meals.