I've been flying US more lately, and I have to say the TPA Club is a reason for me to fly US instead of UA. The staff there are outstanding, and it's always easy to find a power outlet. And it's never crowded.
The worst I've visited is BOS. The lack of T-Mobile or a free alternative is outrageous. Even worse, when my flight was delayed and I asked the agent to check alternative routings (after I had waited 4 minutes for him to finish a personal call), he told me not to worry, because I would automatically be rebooked. He never even checked my itinerary. If he had, he would have realized that waiting to be rebooked would result in me getting home the next day. I guess he was too busy to be bothered. I exited the Club and an agent in the concourse checked my itinerary and protected me on another flight in case I missed my connection. The fact that I had to get an agent outside the Club to assist me is inexcusable, IMO.