I don't know what you like. So, I'll list all possible types of places:
- Museums: There is Museum square (Museumplein), which has most of the important museums. Even if you don't like museums, I recommend going there, because the view there is really beautiful. My recommendations are the Rijksmuseum (national museum), Van Gogh museum, Stadelijk museum (modern art museum), and there are many you can find there. There is museum for bags and purses, too
- Parks and stuff: Vondelpark is a nice park. It's on the middle of Amsterdam. Amsterdamse Bos is the biggest park you can find in Amsterdam. There is a nice lake there which you can rent canoes and go around. There is another big lake not so far from the center called Sloterplas. It's really good. There is the Amsterdam royal zoo called Artis. It's really nice.
- Windmills: it takes about 30 minutes by train to get there, but there are many old windmills there. The place is called Zaanse Schans. It's a small town near Zaandam.
Of course, a canal cruise is a must. You can find them near the central station. It's basically a boat that roams around the canals in the city. You can find tours that tell you some history about the city as well.