I think your choice of area is pretty spot on. Anything in the North Park, Mission Hills, Hillcrest, University Heights areas. Basically check out the areas inside the borders of the 5, 8, 15, and 94 freeways. That are will give you a broad range of costs and neighborhood vibe, but will still meet your criteria. Your commutes from that area would not be bad at all.
It will always be a bit warmer more inland, and you won't experience as much morning marine layer, but the temperature difference would not be anything significant. You're still pretty close to the coast in those areas.
There is a lot of hiking in SD county. From the coast, to urban canyons, to the mountains and deserts out east. A classic book you should check out is:
https://www.amazon.com/Afoot-Afield-Spectacular-Foothills-Mountains/dp/0899978010
I've spent a lot of time in Portland for work, and I love it, but a little gray goes a LONG way for a SoCal native. I hope you like sunshine.
Good luck, and bring some VooDoo doughnuts when you come!