I would love to have time to ride. About all I do is commute. But I would be interested in hearing what you suggest.
Fullerton Loop is epic ride. Not because it is particularly good, but because it is a mountain bike ride in a suburban setting, and because of the wide variety of trails/roads it covers.
BTW, tomorrow (the first Saturday of October) CORBA is offering the
Introduction to Mountain Biking class at Malibu Creek State Park. I took this class several years ago; it is outstanding. I would recommend it to anyone.