AZ, this might be tough...doing the entire coast plus a Hearst Castle tour will likely take more than a day if you're doing it "leisurely."

If you leave Santa Monica at 8am (yawn!) and take off straight from there up Highway 1 (beautiful ocean views), you'll likely get to Santa Barbara by 10am or so. If you don't stop, you'll get to San Luis Obispo roughly by noon. Then it's a little more than an hour to Hearst Castle. Any of the Hearst Castle tours take at least an hour (you'll want to pre-order your tickets which you can do right away; otherwise, the tours may be sold out when you get there...you cannot see the castle from the entrance; you must take a tour to get anywhere near it...if you've never been, I highly recommend it). So that realistically puts you at 3pm by tour's end, and then it's another 2-3 hours up the coast to Big Sur and Monterey. This is all without stopping for lunch, etc.

So...depending on your ability to alter your plans, I'm suggesting another possible schedule.

5/15: 8am Leave from Santa Monica (7am?).
2pm lunch in Cambria (a quaint town just south of Hearst Castle).
Late in the day tour of Hearst Castle for those who want to check it out.
Spend the night in Cambria (there are number of hotels on Moonstone Beach Drive that cater to a range of budgets).
5/16: 9am breakfast in Cambria
Drive north to Big Sur
12 noon lunch in Big Sur
(on your own from there)

I'm up for the caravan idea, but there might be folks who join/end at different places. Between our cell phones, and a general idea of meeting in Santa Monica at 8am, Cambria at 1pm, and Big Sur at noon, we all should be able to find each other along with way, without cramping anyone's schedule.

What do you think?