Are your goals for upgrades only? Domestic or international? Are you interested in premium cabin awards?

I am partial to UA and then to AA. I really like the *A network partners and the routes they offer. This is a personal decision that you have to make. I'd recommend spending some time reading the forums of the various US legacy carriers so that you are able to make an informed decision. With just flight 1-2 times a month domestically, you might have some difficulty obtaining the highest elite tier (generally 100,000 miles or 100 segments) in whatever program you choose. You might have to take some side mileage runs or leisure vacations depending on the routing of your business trips. Where will your trips originate from?

Are you interested in hotel programs as well? Hilton, Starwood, Intercontinental, and Marriott are often thought to be the best programs. Each program has it's own pros and cons. What would you be looking for in a hotel program?

My advice would be to spend time reading the forums and absorbing as much as you possibly can. You'll look back a year from now and be amazed at how much you learn and how much your thinking will change. You will also get some great advice from other flyertalkers in this thread.

Welcome to FT!
Halothane