I thought this eHow article was useful. (See link.) I've always done mine off-center and have never thought they looked bad at all. To me, the centered knobs actually look "less centered" overall b/c they are so far from the crease where the hinges are, which would be the true center of the entire bifold. I know it's the most common way to do it, but the "centered" approach looks weird to me since the knob is 3/4 of the distance away from the pivot. I don't like it, personally. I have always had paneled closet doors, so I have lined them up with the edge of the panel closest to the hinge on the non-pivot door, centered vertically between the panels in the "open" space. This placement also makes the doors easier to open & close. I had a rental w/them centered, and my in-laws' are centered. It's minor to some people, but it does take more force to open & close them and could make a difference if you struggle with any arthritis or mobility issues. To me, the easier to open, the better. (Sorry for the bad lighting in my photo; I just used my phone's camera instead of getting out my good camera.) Here is a link that might be useful: eHow article

Actually it would open inward flush with shelving in the closet, so it won't cut into closet space. My main concern is losing space in the bedroom when it is open!

Thanks for all your comments; very helpful information about the screens. I am also overly rodent sensitive as we just finished ridding ourselves of those that we found were living in our recently bought house. Before that ordeal, I wasn't thinking about the bi-folds much, but now I am definitely very cautious about it! Although I haven't seen them in the yard yet, it is apparently common in the neighborhood so its just a matter of time. Plus we haven't moved in yet (awaiting this renovation to complete). Having gone through the options with screens, I am leaning towards concurring with Patricia that it takes away from the wall's openness. Which means, with my rodent sensitivity at this point, maybe a fully open-able wall is not right for us. Having fixed glass panels would still provide the visual openness we are looking for, most likely. Thanks again for your time, all!

Thanks for your responses. I definitely am not expecting any sort of bargains, that's for sure! I'm more curious about the screens. We have the retractable screens in our casement windows and sometimes they snag. I'm wondering that will be a bigger issue when using them on such a large scale opening?