Amsterdam
Every Wednesday, from September to June (the cultural arts season), at 12:30 p.m., the Concertgebouw treats visitors to a 30-minute concert, which is often a public rehearsal from world-renowned orchestras or ensembles that will perform "officially" later that evening. Concertgebouw: Concertgebouwplein 2-6 (off Van Baerlestraat)
Location: Albert Cuypstraat (in De Pijp neighborhood)
Open: Year-round, Monday - Saturday 9 a.m.-5 pm
Farmer's Markets - Saturdays 9 am - 5 pm
Rijksmuseum
daily 9 a.m. - 6 p.m. and Fridays to 10 p.m
10Euros
Van Gogh Museum
daily 10 a.m. - 6 p.m. Extended hours on Fridays to 10 p.m
10Euros
Canal Cruise
http://www.amsterdamboatclub.com/rides.html
Sign up at Boom Chicago (Leidseplein 12)
Walking
Anne Frank House
daily 9 a.m. - 9 p.m. (budget 1 hour tour)
7.50Euros
long lines, can pre-purchase evening ticket
OLD COMMENTS
More from the Dane... http://www.virtualtourist.com/travel/Europe/Netherlands/Provincie_Noord_Holland/Amsterdam-463377/Off_the_Beaten_Path-Amsterdam-TG-C-1.html
I hear renting a paddle boat and going through the canals is nice. Maybe try a few space cakes first. And the Rijksmuseum was recently remodeled - near the Van Gogh museum. There's some old 17th century sailing boats down near the water that may be cool to tour. These suggestions come from the Danish ops guy, Peter, that I work with. Other than that - he says it all is pretty easy to discover. He didn't have any hidden gems to recommend.
Under walking, I'd also like to check out the Jordaan neighborhood in addition to just spending time walking around different areas. If we want to get out of town for a half or full day, visiting Keukenhof Gardens in Lisse sounds like it would be worth seeing. (http://www.keukenhof.nl/nm/english.html) It is the world's largest and most famous flower garden and is only open 2 months out of each year. It closes on May 20 this year, so we'd be toward the end of the season, but who knows if we'd ever be in the area in the spring again. Plus, it'd give T & I a chance to see some of the countryside. Also, it'd be fun to rent bikes and ride around to see more and since it is popular there.