I do a lot of shipping via USPS, and I like them. However, one thing I learned from speaking with people there. Priority is great, but shipping Ground has a risk, especially for large packages. If you ship priority, it will go out on a truck that day. But with Ground, if the truck is full, and there are just a couple of packages left, it stays until the next day (or possibly the next, when they have room). Large packages, like a bass or cab, are more likely to be left behind. In other words, it probably isn't worth the cost for priority express, but definitely worth it for priority.
