Celebrity has a very restrictive smoking policy. We were on a ship in March and it was fantastic! No rooms, balconies, casinos, resturants, etc...
We will be taking Celebrity on a Northern Euro cruise this May.

Azamara (Celebrity's "upscale line") has an even more strict non-smoking policy. Its more expensive, been on one cruise, but if I could afford it, it would be the line of choice.