If not having a garage is a feasible option where you live, I'd convert the garage space to living space if possible.
If that's not an option, I'd explore extending the left-side unit of the house (the part with the 14' roof) pretty much "as is," and tie it into the garage with a clerestory roof (same as what you've got on the 20' section, with the windows above the garage). Kind of funky, but no funkier than other options and consistent with the existing design.