You can walk or drive to Downtown Disney. Don't go too early. A lot of shops open at 9:30am, some not before 10:30am:
In general this is a nice place to walk around and visit shops and restaurants. Between you see a lot of disney figures, some nice buildings, big Lego statues and a paddle steamer. This is like a Disney park without attractions: only shops and restaurants. But if you like, take a boat tour or go up with the hot-air balloon. In general it seems better to visit this in the evening when they turn on all the lights and the sun doesn't burn you.
If you like lakes and nature, you can drive a few miles to south east and visit lake Kissimmee
and lake east Tohopekaliga, two huge lakes.
And this picture is from Osceola History Site, where you can see a couple of old houses and learn how people lived here more than 100 years ago. They have some nice buildings including a black smith and an old school.