My trips to Amsterdam have always revolved around friends who were part of the cast/crew of Boom Chicago, akin to Second City here (started by a couple of guys from Evanston and, like Second City, a feeder of the SNL/Mad TV casts). The Boom Chicago website has a newsletter for travelers to the city with some useful info and tips on places to go for food and entertainment.
http://www.boomchicago.nl I would highly recommend stopping in for a beer and picking the bartender's brain--would likely be a great resource for inexpensive things to do. The shows are also very good if you're up for that kind of thing.
As for Rijsttafel, I was there a number of years ago for my birthday and they took me to Kantjil en de Tijger which I loved--a table full of tiny plates of mysterious dishes that tasted nothing like anything I'd ever had before--what's not to love! But I could see it being VERY intimidating to a less adventurous eater. I really don't remember anything about the menu so couldn't say if there would be options for her and, at that, I don't know if you can even do Rijsttafel for one...
My only other advice is to avoid Febo at all costs--you may be tempted, especially if you indulge in any of the other "entertainment" options unique to Amsterdam--but don't do it!
Boom Chicago
Leidseplein 12
1017 PT Amsterdam
Kantjil en de Tijger
Spuistraat 291--293
tel. 020-6200994)
Looking forward to hearing where you go!
"Knowledge is knowing a tomato is a fruit; wisdom is not putting it in a fruit salad." Miles Kington