They like to lie around in the sun. Even though it may seem perfect, a wet area in your yard would be a poor choice for this type of garden because it would not allow the plants to go into their summer dormancy and the wet soil would rot the roots. First, there's something you can't do anything about, and that's the weather. If the fog rolls in on a regular basis you should locate the garden area in as much sun as possible. If you are located in a warmer and sunnier coastal valley you can get by with less sun.
Soil needs to drain well.
If your area slopes, that will work. If all you have is flat ground, consider building mounds. Planting on these will keep the roots out of the soggy winter soil. Raised beds or bottomless planters will also work. Just because the plants go dormant during the dry season doesn't mean that they look bad.