chris, I think the only thing blurb retains rights to is the software, technology and user interface from which you build your book, plus, of course, their trade/service marks and logo. I think you own the content and layout. you should definitely look into this deeper and report back whether I got my story straight or not. metaphorically, I think they own the canvas and you own whatever you put on the canvas.
Obviously, Blurb's business model won't give you much chance to make any money, but you can have some nice books in any quantity you want, even one-sies and two-sies.
their proprietary layout software is cumbersome and not too accurate. put simply: it sucks. if you have experience (and I'll bet you do for sure) with other layout platforms, you'll do better using those and importing your work. I had trouble with the two books I put together very quickly as gifts to family getting the image registration right. One of these was a wedding album that to make up for a photographer who shot the wedding but never delivered the results. I was shooting for fun and stepped in long after the fact as favor.
As I'm an idiot when it comes to layout, I struggled. With your background, you can probably come up with something real nice.