The big question in San Diego is what canyons will you need to climb, and will your bike and you get up them. It sounds like you feel the Marin is okay on that issue.

As far as handlebars, you may find that adjusting them just a bit will solve your problems. Mine hurt after about 3 miles, I rotated the bars just a few degrees and now they never hurt. Basically, I loosened the bolt and then fiddled with the bar until it was comfortable and tightened things back up.

Saddles are a personal issue. Mostly you'll have to try out some. Don't be deceived into thinking you need a big mattress. What you really may need are some more muscles down there. I actually prefer as hard a saddle as I can find. It may be a width issue as well. My current saddle is a woman's Avocet O2, (I'm male) and from the wear patterns on the very edges of the saddle I need all that width. Some dealers do have meters that will help you determine how wide a saddle you need.