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)
Located under Q-Park, Waterkant is ideal for sunny days since you can get direct sunlight until late evening. Grab a beer and a table on the terrace and enjoy sunny Amsterdam while it lasts.
Note: if you get a bit tipsy you think you see a double Guggenheim
Hannekes Boom is one of the nicest waterfront café in Amsterdam to have a beer when it's sunny. Close to Central Station, the place isn't crowded by tourists, but you need to be there early to get a seat.