So anywho, the gist:
Clicking on Scheduled Downtime on the quick actions menu on the left would bring you to this page: It's about the same as the current page, but with some "enhancements". There is a drop down for the host add section, making searching for and adding hosts to downtime easier. Note that there's also an add button. Ideally you'd be able to fill out all the fields and then quickly select hosts and add them (the fields for times/comments/etc. would not change as you select hosts, only if you change them manually) to the schedule. Once you click add they go into the list for 'hosts ready to commit'. When you've added all the hosts you want, you can click commit and it will schedule your downtime windows. There's also "With checked" actions at the bottom for deleting, copying, or modifying the various downtimes. Again, not sure how possible or practical this is, but I figured it was worth a look.
Please excuse the crudity of the mockup, I did this in paint...