Been to Budapest a couple of times, the last time being last May .
Excellent spot and very highly recommended.
While there, take a boat-trip on the Danube, take the funicular for some awesome views of the city. There is a hot-air balloon at the main shopping mall that you can go up on, I believe the views from it are excellent. For an experience, pay a visit to the Gellairt (spelling!) baths (not everyone's fancy).
If you can stay in Pest. Loads of sights in Buda while all the nightlife (bars, restaurants) are in Pest.
Food and drink are still relatively cheap compared to home. Good Irish Pub in the middle of town called Beckitts, normally some craic to be had there.
If you are getting taxis, take one at a rank. These are pretty reasonable. I believe you'll be ripped off if you hail one.
Oh yeah, Hungarian women are awesome. My wife has vowed never to bring me back there!!