It would be nice to schedule an announcement to be sent at a future time. I know that you can create a routine to accomplish this task, but that is a lot of work. You can schedule it similarly to a reminder. I think the benefit of these over a reminder is that it would announce on all your devices, but wouldn't trigger a push notification.
"Alexa, in 15 minutes announce... 'It's dinner time.'"
"Alexa, schedule an announcement for Tomorrow at 8am...'Let's go fishing!'"
"Alexa, schedule an announcement every Tuesday at 6PM...'Don't forget to take out the trash.'"