I actually saw a beautiful redesign back in the day (around the time of season 1) that, basically, widened the drive section so that the total width, including the nacelles, was equal to the width of the saucer. The artist also extended the length of the nacelles, but couldn't decide whether he liked them better that way. I did. He also redesigned the deflector dish to make it more, well, TMPish. It was a gorgeous design.
He also did a design that extended the nacelles, but otherwise kept the drive section as it was. However, he changed the geometry of the saucer to make it long and narrow rather than short and fat. It looked great, too.
Wish I had copies.