If you really don't want to be around children, old people, crazy teen agers, people who drink too much, really large people, smokers, people who want to dress formally every night, people who want to always wear casual clothes, photographers, loud music or wait in long lines to fly or to get on the ship, then you might be better off taking some other kind of a vacation. You are likely to encounter most of the above on any cruise you take unless you have a private yacht.
I think variety and unusual circumstances actually add to the enjoyment of the cruise. I have never been on one I didn't enjoy and don't expect to do so. Just book your cruise, get on the ship, grab something cool or someone hot, get out in the sun on a deck chair, and FOGGETABBOTIT. Live and let live! Love and let love!