MJJ - I don't know if you have already taken your trip, but I thought I would reply in case you have yet to go. I have sailed the northern channel islands many times, and believe them to be the best of the "local" islands. Santa Cruz is the most diverse in terms of anchorages, and has well protected spots in most conditions. Strong NE winds (Santa Anas) are tough anywhere out there. Santa Cruz also has great sea caves for kayaking, good hiking and the West end can feel as remote as San Miguel.
That said, my favortie is also San Miguel. Cuyler Harbor is an awesome anchorage with a two mile sandy beach. However, in April it can really blow out there. Even though Cuyler is surrounded by 500 foot bluffs, the prevailing winds whip over Lester Point and right down into the best spot in Cuyler. You need to prepared for cold, foggy and windy conditions. That to me is part of the charm.
With three days from Santa Barbara, you won't get a lot of time out there, but if you like hiking, you should call the Park Ranger in Ventura and ask for a guided hike. (Without the guide you are limited to the beach at Cuyler and up to the ranger station/campground.) When we go out we often make a night crossing to Fornies (Sp?) on the West End of Santa Cruz, take a nap and then try for Cuyler the next morning. If we can't make Cuyler we spend the night at Johnson' Lee on Santa Rosa, which leaves a short morning motor over to Cuyler. The other way we go if the weather is cooperating is to head up to Goleta Point the night before and anchor there, which leaves a managable sail directly to San Miguel the next morning.
No matter where you end up out there I'm sure you will have a great time. I am headed out there the first week in May.