As a former resident of San Clemente, I agree with you 100%. However, don't forget there is no TN state income tax which is a definite plus. We also do not have personal property taxes.
Yes, buying in Memphis proper versus the outlying communities in Shelby, Tipton, and Fayette counties does increase your taxes. If street lights and sidewalks are a priority then Memphis city is for you. As for commuting to and from Memphis, nothing here compares to I-5. You can travel from the Mississippi River to the far east portion of Shelby county in less than 45 minutes.
Regarding taxes if you are 65 and older, I do not have any recent information but I do have link from my website under area information to our TN website. Hope this information has proved helpful.