It depends on what you are looking for. Performance or relaxed cruising will call for different set ups.
For performance orientated chassis upgrades, in my experience, stiffer springs in the front, well adjusted koni shocks all round, polyurethane bushings front and back, shorter front leaf springs, stiffening of the rear axle lateral strut mounts, lowering the car by one to two inches, getting a bit more negative camber front and back and moving the battery in the trunk or behind the seats will transform your riding experience and make the car much more efficient on twisty roads. The price to pay will be some loss of comfort.
For relaxed cruising, the stock set-up with new rubber everywhere is your best bet.