We are much smaller, but also use the Google paid support.
I'd echo the sentiment here: my experience of the paid support for GCP has been universally excellent across Compute Engine, App Engine, BigQuery and Cloud Storage. This is across 30ish tickets, some of them quite complex.
I use the lowest level of paid support, I think it is the silver plan, and have observed similarly high quality levels of support. Sometimes you get a lower level support dude and have to convince him that your issue is real, but overall the support is good.
I'd echo the sentiment here: my experience of the paid support for GCP has been universally excellent across Compute Engine, App Engine, BigQuery and Cloud Storage. This is across 30ish tickets, some of them quite complex.