Just to echo the OP -- the Cloud SQL proxy has been a pain point for me for years, it makes deploying to Kubernetes a PITA, since I have to use a different configuration vs. my dev setup. Whitelisting RDS networks inside the VPS is a feature that's existed in AWS for many many years.
Also agree that Stackdriver is pretty underwhelming, though it does have the perk of providing zero-configuration log capture in GKE.
Lots of problems though -
* UI is super-slow, yet it drops old records when you scroll, so scrolling up and down by more than 100 lines causes a reload of the logs I was just looking at. (Note that e.g. Kibana will do infinite scrolling to load more log entries, but doesn't drop old ones when you scroll, which is much more usable).
* It's really hard to work with large log traces; I'd love a quick way to "show raw logs for this time-period/search" so that I can either copy into a text editor or use browser search to explore. An example use-case here is "select all logs with this request correlator", which could include thousands of logs from a request, then jump around that log stream to look for interesting events. Re-running the search is painfully slow for exploring results like this.
* I've also had problems with alerts; the algorithm used for uptime checks is pretty naive, it just checks if the endpoint was down for the entire threshold period, which doesn't catch a flapping endpoint (e.g. down for 1s, up for 1s). Grafana can be configured to detect that the average latency spiked over the period, even if it's not fully down. This has led to us not being alerted for a production outage, so I've moved our critical alerting off Stackdriver. (Again, the promise here is great; if you could get alerting working as well as Grafana, it would be super-powerful to be able to alert on any synthetic metric generated from any log stream in the cluster. It's just half-baked right now.)
All that said, I've been happy with GCP in general, in particular GKE has made running a k8s cluster a lot easier.