I'm going to have a very large data set (a few hundred terabytes big eventually), but it is very well structured, relatively simple data involving lat, long points (which is why I want some GIS compatibility).
From what I can tell PostGIS can only handle 32TB or so, and I'm unsure what Oracle Spatial can scale to. Amazon's DynamoDB can go up to petabyte scale, but I've read complaints about how it can become rather complicated and be avoided without having a good reason to use it. And using NoSQL for such structured data seems wrong, but I can't find other alternatives for this size. As far as costs go, yeah it's going to be expensive but let's assume that's not a huge problem. Retrieval speed for spatial and temporal queries is the main deciding factor.