My only consternation was that I live in the UK, and most content is only available if you live in the US.. or pay one of the many VPN or unblocker services to grant you the full US version of Netflix. If you are viewing it on a browser you can use things like mediahint or hola but again these are mostly black boxes and don't easily work with an appliance like Chromecast.
I found some links suggesting how this should be fixed by remapping the default DNS servers Chromecast uses from Google's to their own (once you have an account with them). However, this isn't the whole story - Chromecast only uses* Google's DNS servers if your DHCP server doesn't tell it otherwise. Once I figured that out, I then set about finding some free US-based DNS servers and then attempting to configure dnsmasq to configure US DNS just for it (and additionally any android clients you may want to use to control it). Dnsmasq isn't the best documented so this took some doing. Based on this stackoverflow snippet, here's what I use:
If you have a PS3 or other console you can most likely just set one or more of the DNS IPs in their network settings and voilà!
* probably - I haven't tried this