This is a terrible thing to have to do, but I've documented the process here in the interest of helping anyone else who might have to go through it. Everyone knows someone who deserves a memorial.
The first thing we had to do was find a place where we could actually have a stone. So many places now allow only the 'flush to the ground' stone.
We found that Forest Hill in Ann Arbor would allow us to place a stone we thought was appropriate for Amy.
We worked with the folks at Arnet's in Ann Arbor (who we must have driven crazy - returning with a new design every few days for months on end!). They were very helpful in design, choosing a stone, dimensions, etc.
Once we knew where the stone was going, we started driving around other cemeteries and looking through magazines (the industry does have a magazine) at other designs.