Hi joel.
I cannot recommend any specific textbook in english since I am familiar with german textbooks only.
However, any good textbook on analog active filter circuits should explain the meaning of the complex frequency variable since the LAPLACE transform is used extensively in filter theory.
For example, the application note
http://www.maxim-ic.com/appnotes.cfm/appnote_number/733/explains in a nice manner the difference between "s" and "j*omega". Of course, in the real world only "omega" exists, however, the use of "s" opens a very elegant way to describe filter responses with poles in the complex s-plane. Here, the pole location can be described by two specific parameters (pole-Q and pole frequency), which appears also in the filter transfer function - if "s" instead of "omega" is used.
Regards
Lutz