Not a big fan of zoos and animals behind cages, but if you can spot Flamingos in the east-centre of Amsterdam, then count me in <3 ! You can actually see them while riding the bike on Plantage Middenlaan, quite a beautiful scene.
Note: De Plantage next to zoo is quite cool cafe/restaurant, with a mix of vintage style and industrial elements of the old buildings of Artis. Great atmosphere, and ideal for a more sophisticated outing.
The Bartolotti is perhaps one of the most beautiful Museum Houses Amsterdam has, built by someone who once was the richest man in the city, but it's a bit hidden in plain sight. These days, it is run by a group of lovely old ladies, who can't wait to offer you tea or juice. You can walk around the house like you live there.
You have to ring the doorbell to get in.
(picture from Google, by Arjan Bronkhorst)