Apparently I'm already too late to have my say in this, since I wasn't in the mood to go trough this whole discussion in the weekend. (some people don't check the forum while they are watching movies for current challenges

) and this whole discussion has already been decided in two days.
But anyway,
I'm glad with the decision. I'm also for giving Directed by Women, Sci-fi / Fantasy, Silent Era and Western. Actually for the reasons, sol mentioned; those will be chosen in a poll again anyhow, so it seems redundant to vote for them again. I'm all for more variety in the schedule and against permanency, but having seen these challenge win the polls every year, this hope for change seems futile.
As for the voting procedure, like many said before, you should chose what works best for you sol. The biggest advantage of private voting would be indeed that people vote for what they want, instead of tactically.
But if you go with public polls again: I'm sorry to hear that reacting to reaction during that been daunting for you, sol. But personally I don't see the big problem with people commenting on the results about the public poll while it's being held, just means they are passionate about the forum and challenges. I don't think it necessary for you, sol, to react to those comments always, I think those users know the poll is still open (a long time). They just comment on the result so far, like people do in result threads while the list is not completed yet. This is not meant as an attack on you sol in any way, in opposite its meant to relieve you of some of the anxiety you feel while running these polls.
One week is too short for either procedure option, a month too long. I would go for 10 days to 2 weeks. That gives everyone enough change to react. Maybe having the poll run for a shorter time will also reduce the numbers of casual voters who don't participate in challenges at all. Since people who really care about challenges and participate in them regular will probably vote asap as they can, while casual voters might drop in to vote when they feel like it when the poll is open for a long time.