Okay, so I searched and read several of the projector threads and I've been on projector central calculator site. Now I'm more confused than ever (people mention 120" screens but don't specify 16x9 or 2.40 or whether it's diagonal measure or width, etc.).

I'm looking at a 120" wide AT screen (Shearweave?). Seating at 12' and 18'. At the rate my build is going, it will probably be the Panny AE12000, but since that's still years away, I'm figuring the AE3000 for my calculations.

I could mount it at a 17' throw under the soffit which would be about 6.5' above the riser, or 14-15 feet (in which case would I need to put it on a mount that would lower it from the 8.5' ceiling?).

I've read that closer gets better brightness but further gives better contrast and blacks. There's also the possible issue of projector noise.

Do you think there will be a noticeable difference in picture quality between 14 and 17 feet? At 14', will I be able to mount directly below the ceiling, and use vert lens shift, thus getting the projector further away from the viewers?
Any other thoughts or suggestions?
I would like to prepare for several locations, but will be difficult in my case.
Thanks

I have the PTAE3000 and thoroughly enjoying it.

For the projector, my throw distance is approximately 13' 6". This distance (and what I would recommend) places the projector at the minimum throw range for a 2:35:1 ratio 128" screen (according to Panasonic's manual) - by doing this, you maximize the quality (i.e. brightness/clarity) of your 2:35:1 picture.

See this page (http://www.avsforum.com/avs-vb/showthread.php?t=938346&page=5) of my build thread for more info on it.

Thanks for the input Tupalev. After several more hours of research and hearing your advice, I think I'll mount it about 14 ft. Projector Central was only showing about 11 ft-lamberts at 17 ft, (14 fl at 14') but I really don't have any frame of reference other than office projectors. Being in a light controlled room, I was hoping that I could mount the projector further back under the soffit and not be so conspicuous, but I don't want to risk it. I'll plan on the shorter throw, and if I change my mind after I get the projector, it should be easier to move it back than it would forward. I'll try to make accomodations for boths.
By the way, very nice theater you have. I wish I had the opportunity to be involved with the basement plans when the house was being built. What did you use for the projector mount and did you reinforce the back of the drywall? How high is the projector and are there any issues with projector noise?
Sorry for all the extra questions. I've only found a few threads that go into any detail on the mounts, and they're usually for anamorphic setups or talk about hushboxes. Perhaps all I need is a cheap universal mount.

What did you use for the projector mount and did you reinforce the back of the drywall? How high is the projector and are there any issues with projector noise?

For the projector mount, I use the Chief RPA-U (http://www.chiefmfg.com/productdetail.aspx?ProductID=27793) - what I really like about this model is its low profile design, meaning it hugs the ceiling pretty closely without extensive overhang; potentially causing a distraction for those that sit/stand behind it. The wood blocking to support the projector was a misfire as it wasn't installed where I needed the projector, however the RPA-U can easily be installed on a ceiling truss. Though I still strongly recommend you put up some blocking in the general area where you're considering the projector's location prior to drywall.

From the floor of the riser to the bottom of the projector it's about 7'-6", a little higher if you're sitting in the front row. This projector is whisper quiet and I really have no complaints on noise.

Thanks for all the help! That mount looks good. If I ever make it back to my hometown (Springfield, VA) I'm going to have to check out some of the NOVA theaters.