The Grand Hyatt, which is usually more expensive than the Regency, is actually closer as the hotel actually lets out into the lobby of Terminal D at DFW. I'm not sure that the Regency is a 3-minute walk, but it is probably more like 5-7 minutes depending on your walking speed. Either way, it is very doable and easy to access Terminal C. Note there are a few flights of stairs involved in the walk. Waits for shuttles at DFW can be long, and rides, too, since the terminals are so far apart, so I'd recommend this over the Hilton, but YMMV.