That did it, thanks! I didn't even realize that there were some Sync settings found elsewhere. You'd think that the application would warn you or not bring up the options for anything other than "manual" if auto-sync was turned off.
I've not seen the sync widget, but I use the free Sound Manager app to schedule notification sounds to be off during the night hours. Airplane Autoswitch is also handy, as it can schedule airplane mode to come on at night, which shuts down both wifi and network access so it saves battery too if the phone is not plugged in. I guess that's not good for someone who wants to be able to receive an emergency call at night or something though. I ended up sticking with the Sound Manager as my solution.