I fly from the Mid-Atlantic to destinations in the East, Midwest and sometimes the west coast. This generally means that I fly UA and DL with occaisional flights on US and NW.
For years I have generally avoided US, but find that more and more I end up flying on US Airways, since they tend to go just about anywhere I travel from Virginia to Boston to Florida to Wisconsin.
I must say that I have become more and more impressed with the carrier in many, many ways.
The pluses I see are: 1) very dependable service (perhaps due to the shear numbers of quck-hop flights, US tends to get people on board and in the air on-time); 2) positive attitude of staff; 3) willingness to make up for problems (paying for hotel rooms for weather delays, quick to compensate for delayed luggage); 4) abundance of First Class upgrades for full-fare coach, and 5) confortable First Class seating (compare US to DL 1st class and you will agree).
Now, the negatives: Too many propeller aircraft and too few larger planes and long-haul flights.
These negatives cause me to avoid US since I prefer to fly in an upgraded First Class seat, and the prop-jobs do not have First Class seating. I do fly US enough (perhaps 10 trips per year) to respect the good job they do.