Congratulations on quitting smoking!! I think that is just wonderful!! I am trying to do that myself. And right now...it's just not working. I know I need to WANT to quit..and I NEED to quit. Just doing it is the problem. I had quit for four years and started up again! Terrible isn't it?
As for the plateau.....I have lost weight and now I've been sitting on 145-150 for a couple years now. I should be happy that it only fluctuates about 5lbs. but I would like to get back down in the 130's somewhere. I've been there so I know it can happen!

I wish I could give you great advice on how to get pass that plateau...but since I'm sitting in the same situation.....
It sounds like you have great workout plan as it is and you're careful at what you eat, Maybe a change in what you do for physical activity could help? Summer is just around the corner and maybe you can do more outdoorsy activities. That is my plan. I want to drag out that bike that's being unused and use it. And I also would like to walk more. Give myself a variety. Keep from getting bored w/being active.
Keep on checking in and let me know how you're doing. If you ever want to find me, I'm usually posting at the Jaded Ladies Forum which you are more than welcome to join. But I'm always browsing so I'll keep in touch!
And let me know if you find that miracle to getting pass the plateau!!