The weather up there is unpredictable. We went in the middle of summer and got rained on almost every day.
I'd just book whenever you can get a good deal, take warm jackets, and enjoy the gorgeous scenery. All the lines offer plenty of excursions.
As far as cigars (and smoking in general), the rules change all the time. Check the line policy before you book. I usually look at a ship's deck plan and see if they have a dedicated cigar bar. I've met great people in the cigar bars. Even if a line has a decent smoking policy, not all their ships may have a cigar bar. As an example, NCL's Star had a great cigar bar I spent a lot of time in over several cruises. Even smoked one in that lounge once with the Captain. So what did NCL do - during a dry dock they ripped it out to make room for an art auction. I won't be cruising on the Star again.
And I take my own cigars. Less expensive, and I can smoke what I enjoy versus what's available.