I drove from my hotel to Old Town, took the trolley as Tycho suggested. This was two years ago, but it worked out the best for me. Never had a problem with parking or finding a spot at all it was a breeze. Of course I went fairly early but not too early both days I was there.
Spent the third day at Pacific Beach body surfing. I was suprised how few people were at the beach. Had a great time, but the drive back to Albuquerque was agonizing because I was so sore from swimming so much.