WTG donkey. I am a civil engineer as well. CSU Fresno class of 94. Cal Poly has a great school, had a co-worker who graduated from there, just loved it. I am a PE in 4 states now.
San Luis Obisbo is fun, Pismo, Avila beach, all close. Going to be hard to study with all the fun there is to be had.
My advice to you, set your graduation date for 5 years, not 4. Those who try to do it in 4 are oriental exchange students or nerds with nothing better to do than study ALL the time. Most will wash out, and that is what they want, it is probably an impacted program.
Second, take your freshman year and do your elective classes first. Don't kill yourself with the calculus, fortran, physics and ALL the other weed out class they throw at freshmen to get them to wash out. Have some fun first with government classes, drama, crap like that. Believe me, when you become a hardened senior, you'll be able to take the 18 units of pure engineering classes w/o electives...save that for the end when you know what your doing.
Don't be afraid to hire tutors, you can even get them free through the college.
Last thing, good luck. You're going to study your bellybutton off unless you are naturally brilliant. Not to late to change majors either.