Good coffee shop-meeting place - central SF?
One of the most central places in SF is Japantown Center, close enough to Fell/Laguna exit and not far from the GG Bridge, Park Presidio Dr. There's plenty of parking but it's paid in the garage.
The area outside of Murata's Cafe Hana has open first-come-first-serve seating and plenty of large tables and usually isn't crowded during the weekday. I use to meet a client from Marin there with me coming from the East Bay.
Murata's Cafe Hana
1737 Post St Ste 368, San Francisco, CA 94115
Arlequin Cafe. Especially if the weather is nice and you can sit in the outdoor garden. Counter service only, but they have food in addition to coffee and also beer/wine.
There are parking garages nearby. It's pretty much central between both bridges.
You might need to drag a few tables together on the patio to accommodate the group.