My experience on Alaska cruises is that I met and become friends with most interesting people. People on the Alaska cruise are not the party hearty crowd, but ones more interested in history, nature, and scenic beauty.
I agree about Alaska, but the CRUISE LINE which you choose also has a lot to do with the clientele. I prefer Celebrity and MSC. They are upscale, and so are most of the travelers. There are many more exclusive (translate EXPENSIVE) alternatives, as well, if it's riff-raff for which you are concerned. But I have seen drunks from all the spectrums, and they are still boorish and obnoxious.
I like re-positioning cruises for a great experience. You genereally get a longer cruise, at a fabulous price. In addition, since they leave from one port, and end in another, there are less people.
I was looking at an MSC cruise, for SEVENTEEN NIGHTS for $1195 (inside, pp plus air, taxes and fees). MSC Lirica leaves Ft. Lauderdale and ends in Genoa, in early May. Return Airfare is pretty cheap, too. since it ends in Italy, the trip is easily extended to visit sites there. I even have a guy just north of Rome who provides lodging and tours, along with visits to local ristorantes in his area.