Never have I seen a post office that ALWAYS has a line 30 people deep. No matter what season, no matter what day of the week, no matter what time of day. This, ladies and gentlemen, is the DMV of post offices.
No, I take that back. Even the DMV on Flamingo can accommodate my needs more quickly.
Here's the issue: this post office covers a HUGE portion of the SW valley. As far as I can tell, we're talking everything south of the 215 and west of the 15, and probably some more! If that's 10x10miles, they're covering 100 square miles. I live in Mountain's Edge, and Durango and Russell is where I'm forced to go if I have shipping needs.
Now, the cure: USE THE POSTAGE MACHINE! Of course, if you're there for a passport, to pick up mail, or open a PO Box, enjoy the line. But if you're just shipping a box out, use the postage meter. It won't bite. Measure the dimensions of your box and weigh it, then poke the screen a few times. Pay, and you're done! Or, use the flat rate boxes and, just like the commercials, "yes way, no weigh."
Or solution #2: build another post office, for Christ's sake. It's not all cacti down here anymore.