My rule is quite simple: If I've flushed there, I've been there.
Arrrrrgh! You beat me to it!
My rules for declaring I've been in a particular state/country/etc is if I have done one or more of the following things:
1. Spent greater than 4 hours there
2. Cleared immigration, gotten a passport stamp, etc.
3. Spent actual currency there
4. Used the plumbing facilities