We arrive in Amsterdam just before midday on a Monday and will leave first thing on the following Wednesday, so we really do have only 36 hours.

We've been to Amsterdam before, with our young sons, so we've seen the canals, Anee Frank's house. This time we'd like to visit the Rijksmuseum and the Van Gogh, but we'd welcome any suggestions for slightly more out of the ordinary things to see or do.

I've looked at walking tours http://www.gildeamsterdam.nl/MIMEngels.htm but I'm not sure if they would be a little restrictive in the middle of the day.

If you're going during nice weather, you could rent bikes at Mac Bike or similar,and use their self-tour map down the Amstel River. Very pleasant ride - can go, rest and come back in 2-3 hours.

Did you go to Vondelpark on a nice afternoon? Lots of familys, teens, couples just relaxing, strolling, etc.

The kids (or just adults,if kids aren't with you this time) might like to go on the Houseboat Museum - we just did this in April. About 4€, very charming.
www.houseboatmuseum.nl/

If you have your sons with you again maybe they would enjoy NEMO -http://tinyurl.com/282g6k or the Maritime museum www.scheepvaartmuseum.nl.

Scheepvaartmuseum is closed for almost, 2,5 years due to renovations!!!

If the weather is nice, take a train to Zandoovrt and enjoy the beach.

Oops, I haven't been for a few years. Not having young visitors it doesn't figure on my Amsterdam list!