I'm not your level any more, and live 30 miles away in SanPablo.
For good pickup tennis, GoldenGatePark is one of the best, but you have to filter thru the 3.5's and rec players before you attract your level of player. Best during the week, after 10AM, hang around with your best gear and you should be able to get a game within a couple days, depending how bad the weather is, and who shows.
Weekends, GGPk is pretty worthless for pickup, as the weekender rich crowd infests those 22 courts. However, late PM's, a crowd of 4.0 doubles shows up for free court 23, and you can rotate in and dominate (both weekends and weekdays}.
Both Marina and JuliusKahn have good doubles on weekends, certainly 4.5, but timing is difficult, as the crowd tends to show late or early depending on what ...?
Check CityCollege of SF or SFState, like 15 courts at CCSF and 18 at SFState. DoloresPark on weekend PM's can have 4.0 pickup doubs.
Where are you living in the City?