SecondAttempt
Thinks s/he gets paid by the post
FWIW, my general rule of thumb is 1 day of travel for 3 days in a city at a minimum. Of course that can vary with the city. And if the travel between cities is spectacular that can also affects how I adjust the ratio.
That's pretty close to my rule of thumb as well. But the trip between Vienna and Budapest is beautiful if you take the Danube. Maybe after a cruise it is unnecessary but it is pretty awesome.
But I agree with others, pick a city and spend 3 nights. You won't be disappointed.