Another of the great attractions I took my parents to was the Wiener Staatsoper. Since I figured they would rather see a ballet than an opera in a foreign language (and the only other thing playing was Wagner - yuck). Plus, my parents have taken up ballroom dancing, and become avid dancers. A ballet is right up their alley.
I myself love the ballet as well, and I wish I had gone to more while I was in Vienna! Though I am ridiculously uncoordinated, I did take ballet lessons for several years as a little girl. I decided I would make a magnificent ballerina - if only I didn't have to be dictated to and oppressed by the rhythm of the music! Ah well.
Don Quixote is a great comic ballet. I've seen Swan Lake at La Scala in Milan, and the Nutcracker a million times every Christmas season on TV, but that is the extent of my live ballet experience. Vienna does the Nureyev choreography, and it was truly magnificent. I can't help but feel I've missed out on something, going to all those operas all year instead!