I painted the underside of mine.

I sealed the underside of mine with poly but I didn't bother staining them.

Of course I have never sat on the floor looking up at my cabinets. I'm sure my young children see it all the time but they haven't said anything about it...thankfully. :)

Thanks for the replies! I'm enjoying the other threads comments too.

4amblues, can you share what you used to cover your UCL wires? That looks great!

Just a basic cord cover kit from HD, scrappy. I did have to cut off the connectors and a bit of the insulation from the wires in order to twist them together and wrap with electrical tape. (Ack, am I going to be chastised for code violations? My electrical engineer DH said it wouldn't burn the house down.) Otherwise the wires wouldn't have fit into the channels.

Here is a link that might be useful: Cord cover kit

I think that those little finishing touches make a big difference. If you have any seating in your kitchen area, the undersides will be visible. It always bugged me that my old upper cab undersides didn't match the rest. A painted surface is also easier to clean and freshen up - especially if you get "upsplash" like I do :/ .

Fouramblues, your kitchen is really lovely, and your cabinet undersides are too :)

We were going through the same dilemma a few days ago. We have a eating area in the kitchen and the bottom of the cabinets is quite visible and I wanted a more finished look. So my KD ordered panels for the bottoms. and then our contractor will cut circles in it to be able to recess puck like lights in those panels. But that means we have to have the wiring changed from regular voltage to low voltage!