Hi Mark,
Thank you for contributing to the Apple Support Communities.
It seems like iTunes is often unresponsive when you wake your Mac from sleep, but works fine after you force quit and relaunch it.
Here are a few steps I'd recommend first to troubleshoot the situation.
If you have an iOS device connected to your Mac when this occurs, see iTunes: May become unresponsive when connecting iPhone, iPad, or iPod touch.
If you've installed any third-party iTunes plugins, see iTunes: Troubleshooting issues with third-party iTunes plug-ins.
You can also rule out software conflicts in your user account by creating a new user on your Mac to see if the behavior happens there. See How to test an issue in another user account on your Mac.
Best Regards.