OK, I'd tried this procedure before with no luck but for whatever reason it works now. Good Luck!
FROM YOUR COMPUTER:
From your computer's browser, log into your gmail calendar on your computer and select to display all of the calendars you want to be included in the sync options list. You don't have to sync these all the time or have them selected after this initial setup but it is a critical first step. After you verify that your phone is set up the way you like, display or hide calendars as usual on your computer.
ON YOUR ANDROID:
<<< if you're on a limited data plan or are concerned about excessive data charges I suggest you enable WiFi and verify your connection FIRST (this procedure will work either way but it'll be cheaper and faster to do over WiFi >>>
Select Settings > Applications > Manage Applications > Running > Calendar Storage.
Select "Clear Data" (this will clear all LOCAL calendar data but NOT data on the server). Select "Force Stop" (this will force the application to reload from scratch).
The phone will pause for a moment or two when returning to Home and then the calendar will begin syncing to your gmail calendars.
