Obviously, a 3.8+UW is nothing to be ashamed of, especially coming from a grade-deflated private school. His college counselors at school will be better able than members here will, to project how his HS GPA will be viewed by colleges in the context of his school’s rigor and competitiveness. The downside of the UC’s, for him, is that his strong SAT won’t be considered.
As MYOS said, definitely look at CCS within UCSB. It requires an additional application in addition to the UC app. Physics | UCSB College of Creative Studies
If he would consider smaller schools, there are quite a few that are excellent for physics. Reed, in Portland, has a distinctive vibe that might or might not be a fit, but it’s a very strong school for physics, consistently appearing among the top 10 undergrad schools for producing physics PhD’s. Other smaller schools that stand out for sending their grads to Physics PhD programs include Harvey Mudd, Carleton, Vassar, Williams, Wesleyan, Swarthmore, Amherst, and Grinnell. Lawrence U in Wisconsin is also known for the strength of its physics department, and they tend to give merit to match the cost of a UC for CA students.
Have you looked at WUE reciprocity schools? The Honors College at U of Utah, for example, could be a great and affordable option. It has many of the same attributes that people like about CU Boulder, for much less money; and it has an Honors version of the physics major, specifically for students in the Honors College Honors Program – Department of Physics & Astronomy U of Arizona isn’t WUE, but has an excellent Honors College as well and gives generous merit.
If you like Rochester, you might also like CWRU; and Cleveland is easier to travel to from CA than either Rochester or W Lafayette. They have an open door policy vis-a-vis changing majors. (And they have many physics options: Physics BA, Physics BS, Mathematical Physics BS, Mathematics+Physics BS, Biophysics BS, and Engineering Physics BSE.) Show lots of interest if applying to Case - they track this closely.