Sony VPL-HW15 Projector Screen Recommendations
All considered, I think most folks will be best served with a high contrast light gray surfaced screen with this Sony projector. On my Firehawk G3, blacks looked very good, very dark. When I watched the same content on my Carada Brilliant White screen (white, gain 1.4), the image was of course brighter, but blacks just weren't real dark, just bright enough that I wasn't quite as pleased with the end result. Letter boxing on the 106 inch Carada were a dark gray, and somewhat evident. (by comparison, with my Firehawk, and a projector with better black levels like this one, the letterbox areas are barely noticeable except on very dark scenes).
The HW15, which is a little brighter than average in "best mode" but not much brighter in "brightest" mode, makes for some interesting screen choices. Depending on whether you are strictly a movies person, or also watch a fair amount of TV, HDTV and Sports may affect your screen choice. For movie viewing, this Sony has enough lumens for a fairly large screen. it got just enough really well with my 128" diagonal Firehawk G3, a light gray surfaced, high contrast screen, when watching movies with the room fully darkened. In fact, running in low lamp mode even works. On the other hand, it can't quite to fill the full screen when I tried to watch sports at what I consider a satisfactory level. Close, but no cigar!
Where the Sony's brightness can be a problem, is when you want to enjoy watching with moderate amounts of intentional ambient light, such as watching sports with friends, where you don't want to be watching in a "cave" (fully dark room). With a brightest mode measuring in just under 700 lumens, there really isn't any "reserve" for more than a very little ambient light.
Since I mentioned sports and HDTV viewing, keep in mind, when making your decision that a high contrast gray surface will "reject" some of the ambient lighting coming from the sides, which can really help if you've got some not perfectly covered windows leaking light in the daytime, or sconces, on your side walls.