I like Patina and I have learned that a proper clean and wax of a frame can do wonders if the paint was truly shot and the frame had rust issues I might consider a repaint but I mostly don't take those projects on. For a bike I am going to sell on I like to keep the original stuff and replace the consumables but that is mostly 'casue I am a cheap SOB and I want to keep my costs low but I will of course replace broken parts.

For a bike I am going to keep and ride I tend to update the cockpit so I can get wider bars and get them at or above saddle height and will replace the saddle and sometimes brake levers, that is all about making the bike fit and having an enjoyable & comfortable ride.