I would hate to say 0 for Brussels but the other two deserve the time.

Bruges has got to be the most beautiful small city anywhere.

Bruges is small. Why are you taking an all day tour?

We spent most two days there before training to Amsterdam.

There's one spot on a bridge that we nicknamed the view.

We rented bikes for a few hours, drove to the outskirts and rode a bike path around the city. We stopped at the windmills and went into (for a small price) the one that's open to the public.

Bruges is a smaller, nicer Amsterdam but obviously doesn't have the museums.

Two days and 3 should should be fine with the last for Brussels.

I don't see Bruges as " nicer " than Amsterdam.
It is small , touristy and ,yes,charming.
If one loves small town and has no interest in museum it is perfect for a couple of days.
I would spend 4 days in Amsterdam, one in Brussels and one in Bruges.

I would say that your itinerary is very good, do not change it.

I think you have enough time for two of the destinations but not all three.

With only 3 nights in Amsterdam you would have two full days which seems short to me unless you have been there before.

Travel time will eat up some of your days, too. You may have more time if you are not arriving jet-lagged at the first destination and if you have some time for sight seeing after your last night.

Bruges does have some museums, BTW, including the Groeninge Museum with an excellent collection of Flemish art.

I will put in a good word for Brussels, too. It has much more to offer than the Grand Place and Mannekin Pis. It also has excellent museums an incredible collection of Art Nouveau architecture, and many other interesting sights.

Save the time and hassles of changing hotels by staying in Brussels and taking a day trip to Bruges. It's easily done by train.

what southam said.
I also like Brussels ...