Could I get into UC Santa Barbara (or any good UC/ college) with these grades?

I definitely believe you have a very good chance. Obviously I'm not an admissions officer so I can't say for sure but you have the grades, challenging classes, and extracurricular depth that they are looking for. However, a large part of the college application is how you sell yourself...i.e. writing your essay and expressing your personality and interests. Try to choose a topic that is unique to your or that you can write in depth about and that really shows an aspect of who you are as a person. Your grades and academics are good...but I don't think there is any way to "guarantee" acceptance only based on this. With a strong essay though you definitely have a great chance :) Good luck!!