What size would be "relatively small" in your measurement? They're certainly smaller than their Bay Area headquarters, so "relatively", they're smaller. But for FB, at least, there are many Seattle-primary teams (ie, teams where all or most members are in Seattle), especially in infrastructure and storage.
I've worked over two years in each of the FB Menlo Park and Seattle offices, and since the move to Seattle, I haven't missed anything from the headquarters (especially once the BBQ place opened).
I don't know about Google but I interviewed at FB Seattle and was told it's the second largest FB office after Menlo Park, with thousands of engineers and plans to keep growing.
There is no such thing as "Google Seattle-Kirkland", no matter what the managers and recruiters may tell you. There is "Google Seattle", which is located in the Fremont neighborhood, a small and friendly office which I would definitely classify as a "satellite"; then there is "Google Kirkland", located on the other side of a large lake, over in the direction of Microsoft, which is certainly a big place. Still... Google is all about the mothership. Everything is centered culturally on Mountain View (called "MTV" internally).
Well... that's how it was when I worked there; things could have changed a lot in the last five years, perhaps. It sounds like the new Seattle office they're planning to build will be less of a satellite.
