I totally understand Beth, in reality a wall painted with UPW (ultra pure white) flat exterior paint works fine also, as long as you don't have any textrue. Your right, you never want seams.
The Dazian I ordered off of the Ebay store listed as 54" x 108" but actually was more like 55.5" x 120". I ended up making a 2.35 aspect ratio screen or 51" x 120". 50% or more movies are done in this cinemascope ratio anyway. This way I don't have black bars on 2.35 movies like you will have on a 16:9 (1.78) screen. This design is called a "constant height" setup where all movies display with the same height, the only masking that is required is on the sides, which is much much easier to achieve with curtains. Just like in the theaters.
However, there is nothing wrong with using a 16:9 screen. You will just have some bars when watching the wider material.
Also, to achieve a constant height setup, you have to have an anamorphic lens and a DVD/Projector/ or other scaler that will vertically stretch/scale the image for constant height...
fun fun fun, but it is all worth it in the end...
