With a bike, you will have enough range to go to many more places. The highlight is definitely the well-known romantic chateau on an island Červená Lhota, which is about 20 km on a good road. Also Třeboň are with huge ponds suitable for swimming is near. Česká Kanada region with center in Nová Bystřice, featuring a castle ruin Landštejn and WWII fortresses is also interesting. You can easily spend a week or two in the regions, discovering new thing every day just from your bike seat.
A large and nice castle, build half in Gothic style and half as a Renaissance chateau. Surrounded by water and gardens. Offers numerous guided tours of the interior, with varying price. If you want to have a guided tour in English, you have to let them know in advance. It is not possible to get inside the castle without a guide (as with most Czech castles and chateaux). Closed during winter months.
Náměstí Míru
The town's main square features historical living buildings build in Renaissance style. There is a huge Holy Trinity column in the center of the square, which was built to protect the town against Black Death.
Kostel Nanebevzetí Panny Marie
A large catholic church from 14th century. You can get inside everyday for free. You can also climb the 68 m tall church tower for 20 Kč (closed during winter months).
Muzeum Jindřichohradecka
A large museum in a former monastery, featuring exposition of Gothic sculptures, art gallery, nativity scenes and historical pharmacy. Even if you are not interested in museums, it is worth just to visit it because of Krýza crèche mentioned below.
Take a ride on historical steam train. Using the narrow gauge railway, it runs every week in the summer. You can find the time table and buy tickets on their website. The trains usually use the southern branch of the railway running to Nová Bystřice, but some run to Kamenice nad Lipou as well. Their steam locomotive is 120 years old, but even the diesel engines they use on a daily basis are 70 years old.
Městská plovárna
You can rent a boat to paddle on the Vajgar pond, from which you can see the castle.