I saw a thread about Philadelphia cheese steaks earlier, and was surprised nobody mentioned the best available in San Diego:
The Philadelphia Sandwich Co.
3904 Convoy Street (south of Othello), Kearny Mesa, 858-571-0888.
We used to eat there more often when we lived in Clairemont -- nothing like it in La Mesa. The sandwiches are so delicious. and the decor features Philadelphia nostalgia, which is of secondary importance to me.