I can't remember which days it was, but when we were staying there a few weeks ago, we'd occassionally see signs out on the sidewalk for member tours. They had the models open from 7:00 pm to 9:00 pm to just wander through on your own. It wasn't every day, but I know I saw the signs several times during the two weeks we were there. I don't think they keep the models open all the time. In fact, they were locked when we went up on one of the member tour nights. We were a few minutes early, and they hadn't opened them yet. Edit: I just read the post above me. It sounds like they may have expanded the days and times since we were there.
All the guides are at SSR now. SSR is going to be their permanent sales center. If you're still in touch with your OKW guide, you can probably get him/her to give you a quick tour tailored to what you want to see instead of the full nine yards.