Measuring pH is important for knowing whether something is going wrong in your tank and equipment. Getting a magic number isn't important, but keeping the number steady is.
Having plenty of live rock, sand, and shells will buffer your pH and keep it steady. Also, I think making sure all water changes have the same specific gravity will help.
NWoods is right about the day/night swings. Having proper buffers should keep them within safe parameters. But having a nighttime refugium doesn't hurt.