This is my use case for having 16GB on my laptop as well. Being able to simulate the network architecture of our infrastructure with a bunch of little 512MB-1GB VMs is a nice thing to be able to do.
If I'm not doing development with a cluster of VMs though, I rarely go over 8GB.
I'd also be very interested to see how things are turning out for Discourse as a business. I've been keeping an eye on OSS product + hosted businesses for awhile (Ghost being another one now).
Any lists/specific resources you would suggest that cover the things you mention well? This is a topic I'm actively trying to break into the basics of :)
Back when we first migrated to Postgres, Amazon had not come out with their offering for RDS yet so Heroku was the first place we looked. Unfortunately (at that time), there didn't seem to be a way to launch a Heroku PostgreSQL cluster inside of a VPC, so it was off the table for us. I haven't looked at it since but would be curious to know if that situation has changed, or if the nature of Heroku's infrastructure simply prevents it from being workable.
If I'm not doing development with a cluster of VMs though, I rarely go over 8GB.