Realize that if you live west of I-5 you will be overcast and under a marine layer much of the time. Much more so than if you live just a few miles inland. For my money east of the I-5 and west of I-15 is better. The temps are still significantly cooler than east county but you are back from the coast far enough that the marine layer isn’t such an issue. In the case of 4S it sits at the head of the Carmel Valley and inland from San Dieguito Lagoon with no mountains in between 4S and the coast. On a clear day you can see the water from where I live in 4S (no I’m not trying to make an “ocean view” case but make the point that the lack mountains between 4S and the coast gives it the moderating coastal influence.) Thus it gets a nice coastal influence which moderates the climate stays several degrees cooler in summer than further inland. On many days when it is sunny and clear in 4S you will have overcast and marine layer in Del Mar (the coastal community you end up at if you head directly west) is cloudy and overcast. Bottom line. If you can afford it coastal living in San Diego is great. Its cooler but has many more couldy and overcast days due to the marine layer effect. I guess it all depends on your preference. I spent a summer in Texas (1985). I can assure you. The hotter than hell humid soup that is a Texas summer is a far cry from what you get during the summer in the communities east of I-5 and west of I-15.
