My office (5135) is on the 5th floor of McGill Hall (#246 on the map). It faces the south side (Mt. Soledad).
Parking lots P208, P207 (just north of Mandler Hall) and the Faculty Club parking lot P206 (to the east) are the most convenient when visiting either McGill Hall or Mandler Hall. P208 sells parking permits all day. P207 only from 4:30pm. P206 uses coins. At the intersection of North Torrey Pines Road and Muir College Drive, turn east onto Muir College Drive to enter either lot.
In these lots, parking permits are required, and are sold in machines nearby. UCSD visitor parking information is available here.
General directions on how to get to UCSD are here.
Useful map of UCSD facilities is here.