I recently got an Elunevision Reference 4K Tab-Tension 120" screen for my W1070. My projector is 13.5' away from the screen and I sit 12' away from it. I am glad I went with 120" as I was debating between a 120" and a 106".
I would recommend throwing the image onto a wall or sheet to get an idea of what size screen to get. This is what I did for about a month and that was how I settled on getting a 120"
I would look at elite, monoprice or visual apex or jamestown for screens. I am not too familiar with all of the fixed screens but you can also go the DIY route.