Hmn, when I read the title of this post, I thought it would be lotsa suggestions of sweet places to be in Amsterdam... not just the coffee shops.
I got some suggestions here, add more if you know any:
- going to the cinema, while high (bring snacks...)
- going to the Vondel Park, and then get high there
- going to the Vondel Park after dark, and then get high there (if you go more south, it gets less ppl and you can blaze under a big tree near the lake

)
- clubbing, while high, my favorite is the Escape Venue, they got screens on the side-walls as well and it get's really trippy! sometimes feels like you're in space)
- clubbing while high, but with fancy clothes (...)
- going to museums, while high, many museums in Amsterdam...Foam photo museum if you like photography, this can get you thinking a lot! The Sex museum is obvious, near the Amsterdam Centraal station. Van Gough Museum might be worth going to, but I haven't been there. Also, there's a fluoresent art museum -- haven't been to this one, but seems nice -- they got whole rooms completely fluoresent, would be really trippy!
- rent out a boat and get some snacks (careful not to get lost in the channels!)
- Taart van m'n Tante -- this is the name of a cake shop (google for address). The first time I arrive to A'dam I like to get a whole cake to start a relaxing time ... just for me
hmn I'm gonna make some food now... but hope that someone might write some good spots to be at in A'dam that are easily missed if you go just for a weekened.