I would suggest you make a request for NON-smoking for medical reasons. That's the only request we ever make, and we have never been disappointed in the location or view from our room.
I used to let the chips fall where they may regarding location. It is a lot fun not knowing where you will end up. I would request that the rooms be in the same building if you want them to be.
If non-smoking is a must, I agree with the others that say it should be your only request. That way, you will greatly increase your chances of getting the non-smoking without worrying about the other requests.