I have discovered two wonderful conveniences that are FREE courtesy of the US Postal Service! Yes - each saves a trip and waiting in line...
When you are getting ready to go on vacation or be away, you can put your mail on hold from your home computer. Fill out this form at least 24 hours in advance and voila! They will also deliver all the collected mail on the date specified. When I'm getting ready to leave, it seems I never quite have time to make it to the Post Office so this is a great alternative.
The second thing is ordering stamps by mail. You can do this two ways: one is free, the other isn't. If you order them from their website, you have to pay shipping and handling. However, next time you are at the post office, ask for an envelope to order stamps by mail. This goes in your mail box with no stamp and the order is filled by your mail carrier and returned the next business day. They have a 24 hour turn around if it is during the week. If you put your order in on Friday, you will receive it on Monday. And, they always provide a new envelope with your order so you are ready to go next time!
These two things have saved me lots of time and trips to the Post Office - hope they help you too!