The keywording is great, even with just 16 choices. I had an idea that would be really interesting...
What if those 16 fields would hold keyword "groups" ? Just a series of comma delimited keywords that would get added to the Lr keywords. I "believe" that if you have the hierarchy set up like water>river>Yellowstone River that you can just add the keyword "Yellowstone River" and it will add the rest. If you could store a string of keywords it would make keywording really simple in many cases, at least for things you tend to shoot a lot. In this example you could have something like "Yellowstone River, summer, Wyoming, landscape, morning, Zeiss 21" and it would get those keywords as well as the keywords above it in the hierarchy.
Even if we had to type the keywords into the field it would work wonderfully.
John