Out of the properties I've stayed at which have Honors floors, their location seems to be completely random, some have them at the top, some on the ground and some in the middle. In general the layout seems to be exactly the same as other floors. When I get a true upgrade (i.e. suite, larger corner room) it is often not on the Honors floor(s). Sometimes the Honors floor is far away from the lounge floor.
Re OLCI, the 12th floor room is probably classed as a different room type to the ones on the 3rd-9th floors, so the system wouldn't offer it to you
I've been seeing "HHonors Floors" for years at various properties specifically Hilton branded and a few Doubletrees... I always wondered what the point of the floor was. But I think I finally figured it out.
I think it is to help the hotels with their free water distribution program since almost all HHonors Members receive free bottled water. It can be very easy for the hotel on those floors to know that the two waters are free and to make sure to leave those cheap 1/2 L water bottles that they get in cases of 24 for about $2.50 each in those HHonors Floor rooms only and not leave those higher cost bottles of more expensive brand name water that the other floors get that cost the customer $5 each.