Find an airline that you'll be able to fly on a lot and stick with it. Since AA is in your home city, sticking with them would be good. The benefits initially will be sparse, but once you hit Platinum, they'll treat you as well as NW or CO would. You can also try to have your travel agent nominate you for status. Sometimes airlines will give out silver status for free if you move into a high travel role. Since you can pick your airline fly only them and avoid others where possible. Hertz do offer very good service. I would stick with them and don't rent at others. Figure out how you handle insurance with them before you rent. Your company probably has you covered. Find a credit card that you really like. Some of them offer cash discounts for their use so that might be a very good option for you.

Find one hotel group and stick with it. I wouldn't make this decision based on where the corporate headquarters are. We all live in the one country after all. Hilton and Marriott are the most common domestically, but I'd go with a chain that has hotels wherever you will want to stay.

Get good luggage especially a good carryon. Get a light laptop. Get some in ear buds or noise cancelling headphones. THe Bose ones are popular, but not the best. Shure and Etyomic Research offer some great in ear buds and Sennheiser do great noise cancelling cans.

Put EVERYTHING on your credit card. If you pay for cabs with cash make them fill it out. Otherwise, you'll forget what the amount was. Paying cash is handy, but bad as you'll end up losing receipts.

Learn your company's travel policy and find a good travel agent.