If I was still doing trade book publishing I would recommend to my authors that they try blog touring. Conventional book tours have their place, especially for developing bookstore relations and to some degree local media, but a virtual tour via blogs would certainly reach a much larger audience. The return from that audience would be less than from a conventional tour on a percentage basis but probably not as an absolute number, and the cost is minimal.
It does require putting in some time, however. It might be worth hiring and assistant or a professional consultant. M. J. Rose at Buzz, Balls, and Hype offers sensible suggestions. As in any kind of book work, market research is the most important element. The author embarking on such a tour must spend some time researching blogs for sympathetic content and getting to know their authors. Then: “Offer to come and guest blog. Or to do a Q&A. Or to give an except.” That’s sound advice.