Add all your devices and create separate activities for each room (watch TV room 1, watch TV room 2, etc.). Just remember to hit the Off button before switching rooms. If you don't hit the Off button and switch to another room, it will be sending commands to devices in the previous room which won't be received and the devices will be go out sync. Just hit the Help button to re-sync.
If you want activities in more than one room, then start activity A in room 1, enter room 2 and press activity B, enter room 3 and press activity C. When you go back to room 1, hold your hand over the IR emitter (or point the remote away from any equipment) and press activity A again. If you go back in room 2, do the same thing to select Activity B, and so on in room 3.
Note 1: The only Harmony model that I think supports multi-room is the 890 Pro. See post #4 and #6 of this thread:
[Link: remotecentral.com]. I am not sure but I think it does that via its ability to control multiple IR extenders (one in each room).
Note 2: If you do a Search for "room" by thread subject only (from the darn of time), you will find may threads on that subject.