My daughter went to U of Wyoming (still is there as a grad student). It is cheap. I don’t think we ever paid more than $15k per year (before loans) as an OOS student and she didn’t have the top scholarships that your kids would get. Some of the programs are really good, including international studies as the Cheney family provides a lot of money for study abroad and international students. Engineering, especial for hard rock and civil, is very good. The theater program has a fairly new $10m building. (the state funds the university very well).
The Montana schools also have great programs.
It is also very cheap to live in the towns these schools are in, so costs go down when students move off campus (although the dorms are pretty cheap too). My daughter is living on the amount she makes at Starbucks and banking her TA stipend to use next summer for travel.
I didn’t want my kids to take student loans either, and they didn’t for the first year. After that they took some (not max amount) of student loans. I did not borrow Parent Plus or other loans. That was the deal - they had to pick schools we could afford. One went to Wyoming as it was very inexpensive and the other to Florida Tech which was VERY expensive but she had everything covered with a merit scholarship and athletic scholarship. Were these the flashy schools they really wanted to attend? NO. They wanted to go to schools in California but we couldn’t afford them. They each loved their schools and it worked out pretty well.
If they want to stay in California, some of the community colleges do have dorms or apartments near the schools to get them ‘out of the house.’ My kids went to a private high school in California with a lot of affluent families and 50 out of the 235 grads went to nearby community colleges. Most lived at home (why wouldn’t they want to live in $Million dollar houses near the beach?) but some lived in apts near the colleges. CC can be the right choice even if you can afford more.