I'm going to swim against the tide here and say that as a small business owner I prefer not to use a TA. I don't see any advantage and have bumped up against various disadvantages in using the corporate TAs of my clients. I'm sure those businesses with enough clout to negotiate corporate discounts would see it differently.

I too spend a lot of time researching and choosing my flights. But time and money are important to me and I have yet to find an efficient way of communicating the various trade-offs I might be willing to take on a given journey. Often I don't know what they are myself, until I start looking at the possibilities.

I have found mastering the basics of ITA Matrix a real godsend - it saves so much time faffing around and allows me to configure precisely the trip I want. Once that's done, it's trivial to book online with ba.com/aa.com etc, or occasionally via phone.

I've been caught in limbo several times with BA claiming they can't do something on a TA issued ticket, and the TA telling me that I have to take it up with BA that I prefer to deal direct.