I balance non fiction by reading multiple non-fiction books at once and then prioritizing and making time investment judgements based on current needs. I typically am reading 4-7 non-fiction books, where 1-2 are related to the professional development component of my work, 2-3 are related to the research component of my profession, and 1-2 are for personal interest or personal development. I would assume the ability to do this correlates with how comfortably a person is with multi-tasking, which you seem to be. And, of course, I abandon what is not of interest and skim when I am less engaged.
I always keep a subset of these books with me, one in my purse and a couple in my car trunk, and read while waiting in line at the grocery store or other opportune moments. I prefer reading to using the iphone/smart phone when waiting, as I consider myself more productive reading a book and tend to engage in time kill activities on the phone. I also keep 1-2 fiction books going, but limit those to reading at home. 9 books is around my breaking limit for remembering what I read where, but I am sure some people can handle more.
Oh, I didn’t mention in the post that my formula is roughly 50% professional related, 50% personal related, and the personal is divided equally into non-fiction and fiction. I also try to divvy my reading time up at the same proportions.