I myself have traveled a lot in Europe, I can advise you depending on what your want:
For a city trip, there are some must see places out there. I think Rome and Paris are the two richest cities in history and culture. Paris also has a hectic nightlife. The budgets will be substantially the same as what you saw in Amsterdam.
If you want to rent a car and make the road, the Greek islands and the Croatian coast are superb, however, I highly recommend the island of Majorca in spain, which offers incredible diversity between sandy beaches, mountainous landscapes and A luxuriant vegetation. The nightlife is lively (although less known than its neighbor Ibiza) but you will not be disappointed. Prices are about the same as in Barcelona :)