We'd head straight for Birdwell Britches and get our own custom-made board shorts.
Yes, board shorts. Not the cargo pants-spin offs you see at Old Navy, but genuine Angeleno surfer gear. Generally much more flattering than a Speedo, or its spandex cousin, boxer-brief-style trunks.
For as little as $39, you get to pick the color, the print, pocket, and stitching options. Thrillist LA (thanks for the tip!) believes the trunks can last up to a quarter century. Since 1961, this family run operation ("only family answers the phone") has been suiting up sexy surfers under the delightful slogan "quality is our gimmick."