Eric,

A great question, and it reminds me how well the original design and fixtures on our boat have held up for over 25 years. Not entirely sure what all you'd include in "interior", but here is our list:

• We upgraded our galley with a 4 burner stove (from the original 2 burner), and added a microwave/convection oven as well to replace the original microwave. The head cook on board is really happy with those changes. Previous owner replaced the tile countertop with Corian.
• Much of the cushion foam has been replaced inside the original covers. Not really an "upgrade" just replacing stuff worn out. 
• We upgraded the seat for the nav station.
• A previous owner added some fantastic magnetic insect screens for all the opening ports.
• Alpenglow lamp in the main saloon, and LED bulbs everywhere. New shades for the lamps in the saloon.
• As part of a major deck repair we replaced the hatch in the saloon, and added an interior shade and screen.
• We replaced the hand wheels on the companionway with cams.  

One thing that hasn't changed is the original interior fabric Amel chose.  The synthetic velour-like material seems to be pretty bullet proof. We like the pattern, and will change it out when it does wear out, whenever that might be.  I think Bill Rouse has predicted 100 years. A few other things have needed replacing, but in general we have stayed as close to the original design as possible.

It's not a long list, we are pretty happy with Capt Henrie's choices.

Bill Kinney
SM160, Harmonie
Charleston, SC, USA