Lot's of great answers here.
My Trek Cruiser e bike has stayed largely the same in terms of fit other than a stem and handlebar change last winter. Occaisonal saddle height/fore and aft changes, and thats about it. It's the bike I ride the most.
The bike I ride second most would be the Opus. I was CONSTANTLY making changes to it recently. What felt right, only felt this way for about one or two weeks of fairly consistent riding. Then it was back to the drawing board. I was consistently adjusting the handlebar stack/reach into a more aggressive fit, until one day, I realized that not only am I in the most sporty riding position I have ever been in, but the ride was amazingly comfortable with almost zero lower back strain on relatively longer rides. I took this week off from any "spirited" riding on the Opus. Eventually I will have to switch away from my surly truck stop bars with their 3cm rise and very shallow drop (from the stem clamping area) to continue adapting to the sporty/comfort blended riding position I have been working toward for 1.5 years now, ever since the story with my Norco.