When you go to the Opera do you see tragic Operas or happy ones???? I mean the story line ???

Those are three very different choices. Cleria Rusticana is a one act opera so it is short. But I think it is a little boring. It is usually paired with I Paglacci, which makes it all worth it. My personal choice would be Carmen. I prefer the French composers to the Austrian. But, Don Giovanni is Mozart's best. So, you can't really go wrong. So, if you prefer Gypsies going through Spain, singing in French, falling in love and meeting a tragic end, go see Carmen. If you want to see an arrogant, womanizing noble man get it in the end, see Don Giovanni. If Cavalleria Rusticana is not paired with I Pagliacci, I would avoid it.