I'll be in San Diego tomorrow, where to run early am Tuesday?

Where will you be staying??  My family has a house along the bay and so we sometimes do a "Bridges" run/bike/skate  Its around 5mi along the boardwalk around the bay and up over the bridges on Ingraham and Mission Bay Blvd back to the boardwalk. 

http://www.beginnertriathlete.com/discussion/training/map.asp?routeid=169872

I've done that a loop before.  The Sail Bay section in particular is nice.  Most of it is on concrete paths or sidewalks IIRC.

However you have to add the beach.  You can park say down at the south end near Mission Beach, or a little further north near the amusement park.  From the amusement park you can easily cut over to the Sail Bay loop and do an out-and-back, then hit the ocean beach for a run north say to the pier, or to Palisades Park then cut up the hill to run La Jolla Blvd, then run back south.  I've gone as far as 15 miles with this route depending if I do a full loop around on the map above and how far I go into La Jolla.