As dog mentioned Hotel Circle is where a lot of travelers stay. There is always a lot of traffic from tourists/ conventions/ business travelers. Good in that frequent visitors isn't suspicious. Not so good in that it can be targeted by uncle leo. There's a lot of hustle and bustle, so... If you don't mind that, it is convenient.

For a more upscale or quieter experience (while still accessible) I'd try La Jolla or Del Mar.
For quieter but not so upscale, you could do Mira Mesa or Rancho Bernardo.

Depends on the experience you're looking for.