I’ve done a similar move as you’re considering (lived in lower Fairfield County, CT, commuted to Manhattan) and moved here about 8 yrs ago. We also had similar criteria to yours and same feelings about how to raise our family.
FWIW, we landed in Del Mar, which is not perfect, but we still feel fortunate to live here. It will be tough to find what you want under $1.75 mil in Del Mar, and you won’t find the acreage. But your mindset will probably adjust on that and several other points when you get here – for example, instead of lot size, you might evolve to wanting a yard with privacy or a view. I think you’ll find that the weather allows you and your kids to be out at the beach or other local parks, and you won’t miss having a lot of land. Plus, the cost of water is getting so crazy here that even if you have drought tolerant landscape (as we do) without a lawn, you may not want to have more than about a 10,000 sf lot (and I remember being alarmed/amused at having lots measured in square footage instead of acres, but you get used to it!)
Many people on this site have strong personal feelings about which areas are “best” and like to defend them but some, including bearishgirl, do not have firsthand knowledge living in the area you’re leaving so do not speak from experience on that angle. I wholeheartedly agree with SD Realtor that you should come out to the area and rent first, get a feel for each town/area of SD and decide for yourself which is best for you and your family.
Again, feel free to PM me for more info, as I’m wary of getting into yet another debate here about which area is “best.” Obviously, what’s right for me may not be right for you so I don’t feel a need to defend Del Mar or even coastal North County as the right place for you. But I’m happy to privately offer my opinion and observations on the area, coming from the same area as you will be leaving, and with many of the same thoughts as you have about how to raise a family.