I use 5w-30, also in bay area.
Imo 20 oil is too thin. Anecdotal story: I used 5w-30 in my 2010 Genesis coupe that said to use 20. I put 80k miles on that car with no issues.
Imo, most cleaners will work well. What you need is several your choice of microfibers, shop towels, paper towels etc. Streaking typically occurs because the towel you're using gets gunk built up and not truly clean anymore. For a windshield I would use 2-3 microfibers to get it clean.