There are many great uses for GROUPS in Revit. I just discovered another one. If you have a design decision to make and are unsure of which way the client will go, so you decide to use Design Options.. HOLD EVERYTHING. There is a much simpler way to do it.
Create a group, let's say an arrangement of furniture. Move the group's insertion point to a known location.. like the corne of a room or in this case, the corner of the fireplace. (The insertion point is the little x/y axis that shows up when you select the group.. it's dragable).
Then delete the group! Yep.. just hit delete. (it stores in the project, trust me)
Now, create another group.. with another furniture arrangement. Move this new group's insertion point to the same location as the first group.
Now you are ready for the magic. Simply select the group and swap it out (in the properties dialog box) for the other one. BAM. Works like a champ. The insertion point holds the group's location. So for a quick design decision.. you don't have to set up Design Options if you don't want to.
There seems to only be a couple drawbacks. You can't set up a view where one of the groups is visible and another view where the other 'swapped out' group is visible. So it's a manual process. The other drawback is that the groups, when swapped out, don't retain any visual overrides.
Other than that.. this is the way to go!