Yup, you can pretty much buy into any of them thru resale, just have to watch for them. TSS usually has a good selection, although no BWV at the moment.
I am currently battling with the decision on where to buy. Personally I think BWV are my favorites (although I haven't been inside ANY of them yet), I've seen the outside and quite a few pics. I've been calculating the upfront costs and remaining time, which is pushing me towards SSR and OKW. Maintenance fees are lowest at these 2 right now as well.
I think if you don't care exactly where you stay (just as long as you are there) you'll be ok. Others have mentioned that if you want to stay at VWL for Christmas you'll have to pretty much get points there. Same with BCV and BWV for Food/Wine Fest... I'm not that difficult to please.