This is for my own future reference, since it was hard to find in the documentation and I'll probably need it again in the future.
The things you can create that collect together commonly-used sets of printer options, to be used with the slash modifier to the printer name on the command line, are called instances. Global instances are set up in /etc/cups/lpoptions and per-user instances in ~/.cups/lpoptions. Per-user settings (including choice of a default instance to use instead of the per-printer default) will override the global ones. Beware the lpoptions command, which likes to store your selections permanently in your per-user config file so that subsequent global changes will not be visible to you. Some per-user default settings also appear to silently override per-job settings given on the command line.