Just make sure you are not going on a Med. itinerary. We were on a short 4 night cruise last summer and while no one was smoking inside, the outside smoking areas were not enforced at all. People were picking up ashtrays and just taking them with them wherever they wanted to go. It made being on the pool deck like being inside a bar.
I went on Disney on the Med and did not notice the smoking, on the ship, we were in the ports 90% of the time! Also, I am not afraid to say something to a CM if ppl are in the non-designated areas, they have rules for a reason, just like parents who think it is ok to let their kids come to the adult pool, if a CM does not say something, I say something to the CM. And, honestly, as long as I get breathable air at least inside, surely there will be somewhere outside for me to enjoy smoke free. It is just inescapable if the smoke has permeated the interior of the ship (like my experiences on Princess). My experience has been that it is completely dependent on who you end up sailing with, some cruises may be better than others, even on the same ship, but I would like to enjoy common areas of the ship and find my lungs just won't tolerate as much anymore before I get sick.