Ok, I'm going w/the 1080UB. Yay!
Net up: I'm having an electrician come by on Sat to run all the in-wall wiring/cabling and I need to figure out where to put the wall plates for the video inputs on the ceiling. If I'm understanding this calculator correctly:
http://www.projectorcentral.com/Epson-PowerLite_Home_Cinema_1080_UB-projection-calculator-pro.htm ... I should be able to do a 102" screen at ~15' (anything b/w 9'11"-21'4" is fine, but 13'8" is ideal, right?) So, how should I figure out where the plates should go w/out knowing where, exactly, the mount will be installed (let alone which mount to even get)??
There's a fair amount of reading that you can do regarding screen size, but very much a good deal of it is personal preference.
Generally, screen width is recommended to be about .66 times your viewing distance for THX standards in a theater. So, a 15 foot viewing distance makes your screen about 10 feet WIDE (not diagaonl), and that will give you a similar effect to sitting the in center seat at a good THX movie theater. If you like to sit in front of the center of the theater, then go bigger, if you like to sit more towards the back of the theater, than you go smaller. If you have two rows of seating, either pick a row as 'primary' or pick a distance in between the two so you have options.
The projection distance is ideal, IMO, for that size. About 1/3 of the way back in the zoom range makes a ton of sense.
PROJECTOR PLATES:
Is this new construction which you are having wired? If so, then DEMAND 1" conduit (at least) be run to the projector location.
Also, if you haven't done your homework on properly wiring a 5.1/7.1 audio system, now is the time to do it, and ask questions.
Remember, subwoofers most commonly need 120v power to operate, and use coaxial audio cables, not speaker wiring.
Also remember: The recommended cabling to run to ANY projector that is going to have wiring behind drywall is as follows:
1 HDMI cable
1 VGA cable
1 component video cable
1 composite video cable
1 piece of cat 5
For grins, you could add another HDMI cable and a second piece of cat-5.
I think the spot your chose, for that screen size, is perfect, but if you do want/need to go a bit bigger with the screen, then you will want the projector back a bit more.
I would strongly recommend this mount:
http://www.peerlessmounts.com/dyn/Products/BrowseProduct.aspx/modelID/165645/productID/165644/categoryID/193
Note: Available for far less here...
http://www.buy.com/retail/product.asp?sku=205003132&listingid=11414131&dcaid=17902
If you know EXACTLY where the projector is going to be mounted, then you can actually just have all the cabling come through a small hole in the celing, and put the mount right on top of it. Make sure studs are in place to support the projector mount. Hang the projector on it, and fish the wires through the mount to the back of the projector for a clean appearance.