One word - GO!

Budapest is very nice, these days very reasonably priced (the local currency is 20% down from last autumn)

There's a lot to do and see - 3 days will probably make you want to come back for more.

(word of warning - I was born and raised there, so I'm probably somewhat biased )

As for Prague and the Americans - I think this myth roots in the 90's when everybody and his uncle swarmed from the States to Prague to follow Kafka's footprints and write the new AMERICAN NOVEL. These days the crowds are probably stag- and hen-parties from Birmingham or Leeds.