I think the apron was the same as the decking...unpainted wood. The inside flooring was also unpainted wood, although it was stained.
Can't fully remember 100% though on the apron, as last I saw it was in the early 1990s. But we were lucky enough to get a tour inside. Amazing how it was essentially a giant time capsule.
Here's a pic of a kitbashed Gomez store on our G scale layout:
And here's a thread about the Gomez store with some posts including pics:
Gomez Store
For more layout pics, click the link in my signature.
Matt
Lake Forest, CA
Click Here for my model train photo website