I've been slogging my way through my 150+ devices, some real, some virtual and adding them to rooms to future proof my setup. Scrolling down to the next device is getting tedious.
Here's the tip: Click the Rooms column header to sort by room. Unassigned rooms will be at the top, no more scrolling.
I'm looking forward to whatever features are in planning. Crossing my finger that every room will have an innate State Machine someday. Instead of stacking rules, we'd just define outcomes based on states. I believe that would be more intuitive to new users. Possibly the new killer UI that makes HA mainstream.