I'm not going to respond to
all the comments and views (although the sheer amount of them does show that at least the concept is worth pursuing, just the method needs tuning).
Please keep them coming, though. I'd love to get this right!
I'll take a stab at a few of them:
Andy K - Like APUG itself, anything non-digital goes in the Challenge. Feel free to blast in with some colour, and thanks for pointing out this misapprehension; I'm sure you weren't alone in that belief.
Neal - I like your ideas, especially the placeholder graphic in the gallery; I should be able to come up with something for that. I agree that the current polling system seems to be a lot of palaver. However, if we go for the yearly selection, what happens if someone comes up with a cracking theme halfway through the year? Or a new member joins with a radically new way of thinking that really appeals to everyone? A quarterly polling system might give us more flexibility and a summary webpage (as per David's original suggestion) would certainly help with the clarity...
waynecrider - Thanks for your confidence but I'd rather not get into a situation where I'm picking the themes unilaterally. That way, you just get what flicks my switch and Cheryl might never get her Fairytale theme (where the hell am I going to find two kids called Jack and Jill and a bucket?!

) I'd do it this way on condition that
all practical suggestions go into the hat and I pick them out completely at random.
chuck94022 - I hear you, but I'd rather not turn this into a competition (we're having enough trouble with polls as it is!). I really like Ailsa's original concept, and that's what I'd like to stick to. Comment and discussion is very welcome, either on the month's Suggestions / Discussion thread or in the Challenge Gallery comments
MattCarey - Thanks for the thought (and I mean that!), but I can cope with this level of workload, no worries. I'm also happy to host and maintain a webpage summarising the Challenge and the current theme (provided people are prepared to put up with my crappy HTML! Sean I ain't!)
Tony - Nice to have you back on the roster! Erm, I'm going to duck the nails! There's already a looooonnnng thread running on a very similar subject, and I'd rather not mix this one in with it!
Ole / Sensanjay - Yup, I'm having trouble with the monthly timetable too!
Thanks for all the responses, suggestions and ideas. Please keep them coming.
All the best,
Frank