I built five of these bookshelves for my living room. I wanted them to fill the one wall, so I just divided the length of the wall by five to determine how wide to make each shelf. Also, because I was building several to be pushed together, I didn't want the bulk of 2 by SPF, so I used laminated pine shelving. Two eight foot boards were needed for each shelf, and that left very little waste. I love how they turned out. I blogged more about them (including dimensions) here http://skonkers.blogspot.ca/2014/07/home-is-where-shelves-are.html
Built from Plan(s)
Estimated Time Investment
Afternoon Project (3-6 Hours)
Finish Used
I primed, then painted with CIL Artesian White
Recommended Skill Level
Beginner