Re: Upper Cabinet Design
If you want to be able to see through te peninsula area, cabinets would have to be 6' above the floor, but that's pretty much non-functional for everyday storage. Your 30" option would put them at 66", which seems a reasonable height; many people could access the bottom shelf of these cabinets, and while seated at the bar, the sight line would be clear, and not a head-bager.
For hanging, you could try 3/4" iron pipe with a threaded rod inside. It would be possible to tighten the rod against the pipe sleeve and get a level, wobble-free fit. The sleeve would need to bear against wood not drywall at the ceiling for this to be trouble free. If the cabinets attach to wall or other cabinets and have just one floating end, you could probably get away with a single rod/pipe.
Remove not the ancient landmark, which your fathers have set.