These are all defaults, by the way. Subnets don't have to be /64 - that ended up being the default by historical accident; though it's nice that it forces every ISP to give you at least a /64 which you can subnet further if you want to, though without SLAAC.

Privacy addresses should be used for outgoing connections. Don't treat one as a static address. If you need to write down an address, give that machine an easily remembered static one.