Here are a couple other options to consider... you could put in a unit with sidelites and one opening door in the center, like this - not the greatest example, but you get the idea:

You could also do a slider that partially slides onto a fixed panel. Again, not the best example, but just to show how it works....

You could always sheet rock in the opening to make it a standard width and use a door that matches the other door in the foyer. Save the trim to reuse it.

Love the slider idea, and using french door still keeps it open and let's the light in. But would have to think through design of them so it matches style of rest of house. Not sure about the Sheetrock and shrinking the door, but will keep that on the list

I was thinking much the same as Annie. Either sheetrock in and have one standard door, or do a double door look but have one side fixed (a single-side slider would do this). The glass doors Olychick posted are pretty, but I don't think glass will give you the sound protection or privacy you'd want in an office. (ETA: At my old office we had a glass-walled conference room that everyone called the Fishbowl.)

Definitely agree on the fishbowl. I think if we used any glass, it would be on the top third of the doors / sidelights, and not for the full thing.