Amsterdam for 3 days - what not to miss

Any good guidebook can tell you the "must sees" so you might want to start there. Here are the city's highlights in a nutshell but you need to do a bit of preliminary work yourself. I would suggest starting here: https://www.ricksteves.com/europe/netherlands

Canal tours
Rijksmuseum
Van Gogh museum
Museum of the Resistance
Anne Frank's house
Odea Kirk
Begijnhof
Vondelpark
Royal Palace

Van Gogh and Anne Frank were the highlights of our trip to Amsterdam. Note that Anne Frank tix sell out far in advance. We were not huge Rijksmuseum fans due to a lack of interest in the Dutch masters but I know lots of people like it. Consider a canal cruise.

Thanks - we really didn't have time to get guide books or study up - trip just came up a day ago and we leave tomorrow

Obviously, folks will always recommend museums and historic churches or buildings, and those are important to keep in a travel mix. I generally prefer sticking to a "one major cultural" item per day rule and then using the rest of the time for general exploration of a place.

A few places like the Van Gogh and the Anne Frank house will be tough (likely impossible) to get tickets for those, but the Rijksmuseum ought to be on the "do" list and folks seem to really like the Resistance museum (never went), so that might be another of the three to go to. Also, a canal tour is a great break - an hour or more just cruising through Amsterdam is cheap and fun.

But, with the indoor & "serious" items done, you then have nice LONG days to spend exploring the city and surroundings. The RS city walks are fine (nothing spectacular), but they can form nice ice-breakers to the city. I will push bikes on all who can ride. I think - especially in the Netherlands - it is the must-do thing for folks. It also provides that huge opportunity to get around quickly and enjoyably. You can hit not just the Vondelpark, but MANY parks. Ride from Vondelpark to the Westerpark to the Sloterplas to the Rembrandtpark all in a relatively short time taking you through neighborhoods, past windmills and canals, and in and out of these neat parks. Or, ride down to the Centraal Station area and hop the free ferry (there are several) and get to the suburbs to start exploring further afield - easily reaching places like Broek on Waterland (or even further to Edam). Or head south from the city to Ouderkerk aan de Amstel - again riding by neighborhoods, water, windmills, and farms.

So, a few of the regular must sees ("serious") items are still available, but the joy I found in the Netherlands was that it was just so easy to get out and go - no real plans for the day beyond an idea for a place to ride - and then just riding. Stop all over, have picnics, pet some goats, take lots of photos, buy some cheese from a local farm shop, take a ferry or two, and enjoy the ease of being there. No worries of not finding good food or the locals not understanding your poor attempt at their language or even of getting lost. It's a pretty darn easy place to just go and find fun things to do that aren't in a guidebook.

JR, it would be helpful to know what your interests are. Do you like museums, history, outdoor parks, eating?

Easy on the museums, mostly outdoor attractions, like the idea of a canal boat ride, eating recommendations, and anything unique that would be interesting (not a lot of museums.) Figure the Anne Frank house will be hard to get tickets to but maybe stroll by?

I think Mardee pretty much nailed it. The only things I would add (cautiously) are the Museum of the Canals (I know you said you aren't big into museums, but this one gives you a good understanding of the city as it was built and developed and it isn't too big). And the "Red Light District." Not my cup of tea, and maybe or maybe not yours, but it is an "attraction" that many people find worthwhile to walk through. Lastly, the Begijnhof neighborhood is one Rick recommends in his books and is a contemplative little square in which to take a stroll.

Two quick thoughts:
-In 2013 we took a walking food tour. Lots of interesting tastes of herring, cheese, liqueurs, chocolate, even prowled a grocery store. A quick internet search brings up lots of options so you can probably book one on short notice.

-Download some of the Rick Steves Audio walking tours, just like having a guidebook in your headphones. You can listen to them on the plane if like me you find it hard to sleep.