<p>Cal Poly SLO compares favorably to many UCs. It’s just a notch below CalTech.
However, since financial aid is a concern, you should not apply ED. You need to be able to compare financial aid package.
If you have the stats for Cal Poly SLO, you’ll get in RD. However, applying RD will also provide you with decisions from the California perenials (CalTech, Stanford, USC, HarveyMudd). This way you’ll be able to pick the cheapest school, making your parents happy. In fact, you could actually tell them this: you’ll apply RD and on May 1 you will automatically choose whichever school that admitted you is the cheapest for them.
Also, keep in mind that since you have a sibling in college, that will be used to decrease the expected family contribution for you - their EFC won’t be twice what is currently is for your sister :).
Finally, schools like Stanford have a lot of money and a family who makes $115,000 would definitely be mid-range middle class for them so you might qualify for a lot of financial aid.</p>