I've been lurking in these forums for a few months now, but just finally registered today so I could respond.
I'm in San Diego, Serra Mesa area, which is just up the hill from Qualcomm Stadium.
Pro-Mustachian things about San Diego that immediately come to my mind: The beautiful weather makes it easy to bike and to grow your own food in your vegetable garden (even if it's just a patio garden). Also, endless amounts of free, outdoor activities to enjoy... no need to pay $ for gym memberships or indoor entertainment here. Also, you're not very likely to have a need for heat or air conditioning in your house/apt.
Anti-Mustachian things: High housing costs and car culture.