Good information in this thread. I use the adjustable unit pictured above with the gauge. I would caution you to not leave the regulator in use or stored in freezing weather. Water gets into the spiral pressure tube, also known as a Bourdon tube. Should it freeze, the Bourdon tube is distorted and the needle is no longer accurate. (Trust me on this - experience)
The only other item I'll mention is that I always install the regulator at the valve, protecting the hose. I've seen an overpressured hoses that looked like a snake that had eaten a rat.
But, truthfully, I rarely used a regulator nor hook up to city water. I fill my water tank using a filter and operate with the pump 99% of the time.
Brad