We'll be in Amsterdam for 6 nights next April and are contemplating a sidetrip to Bruges. Is it resaonable to do it as a long daytrip?

The train takes 3 1/2 hours (with a change in Antwerp), and there's a substantially discounted fare for same day return if you leave Amsterdam after 9:00a.m. Looking at the train schedule, our best bet would have us in Bruges at 1:00p.m. (earlier if we paid full price fare), with departure at 8:00 p.m. to get us back to Amsterdam at 11:30.

Anyone done this? Does 7 hours do justice to the town? Got some suggestion for an itinerary (sights, restaurants/pubs, walking/biking tours, etc.)?

That's a lot of time on a train for one day for me, but it is do-able. You can definately hit the hightlights in Brugges in 5-6 hours. The tourist office has tours, and there's a pretty cool boat tour that takes you through the canals and points out various bits of history. And a walking tour you can do yourself using the tourist guide. However if you can, I'd suggest spending the night here just to get the most out of it when the day trippers are all gone.

I think it's a waste of time to go for just a few hours. Before you'll be in the city centre (either walking, waiting for the bus or calling a taxi) some more of your precious time will have passed. Half an hour is easily gone! Same for your return.
Try to stay overnight.

Thanks for the input.

The alternatives for an overnight would be (1) spend our last night in Bruges and take the train back to Amsterdam airport for our flight out, or (2) go mid-week, leaving the bulk of our stuff at the hotel in A'dam and travel light to Bruges.

Mt wife and I found it very convenient to take the train directly from Bruges to Schipol on the day of departure. We spent 3 or 4 nights in Amsterdam, our second visit, and 4 in Bruges. One day was spent with the Quasimodo Flanders Fields Tour and we easily filled the remaining time. Our trip was the first week in November so we had early darkness but blessedly uncrowded surroundings.