Newport Beach, CA.
We just moved from there to Chicago last December and it had almost perfect weather, 70's-80's all summer during the day and in winter it is 60's during the day 50's at night. Once in a blue moon we had a night that dipped to 48. We had several days in January that it was high 70's. No humidity, very few bugs, clean, clean, clean. It is not cheap to live but you don't have high heating or cooling bills either. It would be my vote for cooler summers/mild winters.