The National Ballet is based in the Muziektheater in Amsterdam. I've been to many productions of this company and always enjoyed them. Perhaps the standard is not quite the best I've seen (I think the Royal Ballet in London for example is better), but it is still very high. Moreover, the prices are very reasonable, so I can go as often as I like.
The Muziektheater is a pleasant environment to watch ballet. It is located near the centre of the city and is easily accessed via public transport. I always enjoy the view over the Amstel when having a glass of wine during the interval.