University Heights is a hip neighborhood filled with young professionals. There is an abundance of nightlife on a small strip in University Heights on Park Blvd and is one of San Diego's oldest neighborhoods.
One of my favorite places to eat brunch is at The Farmhouse Cafe, delicious rustic French style cooking- http://www.paintingandvino.com/
Trolley Barn Park has a great playground and plenty of open spaces for laying around or other activities. In the summer's, there a weekly free concerts in the park.
American Voodoo is a unique restaurant that combines California style cooking with Creole- http://www.american-voodoo.com/
There's always a wild party going on at Small Bar- a great neighborhood place with good food- http://www.smallbarsd.com/
If you're into music at all, definitely check out Folk Arts, a rare record store- http://folkartsrarerecords.com/