Don't forget that most domestic US airlines now $20-25 fees for the first piece of checked luggage, $25-35 for the second, and whopping fees for overweight bags. Southwest is the best in this regard, no fee unless overweight.
If you are going to be flying around in the US, you might prefer to travel lighter and do laundry/dry-cleaning instead.
Airline baggage fees chart, updated - Airfarewatchdog
If you go the carry-on route, check the sizes for carry-on on domestic US airlines. Also, when the overhead bins are full, the airlines will often gate-check your carry-on with no fee.