I didn't know that San Diego was the 8th largest city in the U.S.
After my research I put a 1000 to 1450 price on the name. There are more than 50 cafes in San Diego according to yellow book. There are even more restaurants. Competition is stiff so I for sure believe you can find a good end user.
Also another point to consider while selling this domain is San Diego Cafe spells and translates the same in Spanish. This is a good point to consider while selling this name since San Diego is so close to the Mexican border and receives many Mexican visitors.
That is a great domain. Low $X,XXX's if I were to buy it, but I'm sure that with like other geo domains, cafes would not pay 1,000 Dollars for a domain name.
Have to agree with the others; nice usable name, many end users, but all the end users are small business, and most cafes don't do much of their biz online unless they're into catering; most likely use is for a basic info site, blog for one of them.
Likely sell in the $400 - 600 range realistically and easily, up to 1K or slightly over if you find a real eager end user... but most of the higher end cafes are branded and would want to adhere to their branding.
Fine name though, clear use for someone and if you keep the price real should be a quick sell.