As a personal exercise last year, I took a light twin concept of my own through Roskam's Part One. The configuration stood up fairly well to comparison and I learned a lot about how a choice in one part affected the others, including fuel weights, landing gear weights, and cabin size. Roskam considers things that don't get discussed in great detail in other books, yet can make or break a design.
I haven't been into the subsequent books in great detail, but they're nearby on the shelf, calling out to me.....
STF