I have similar thoughts sometimes. My usual reaction it to plan as much as possible, but sometimes this spoils the surprise or leads to less adventure. It depends on what kind of mood I'm in and where the ride is.
It's funny I was just re-reading a post of mine about my first CT trip (literally minutes before I came over here and read your report), where I purposely studied the route as little as I could get away with. It was actually a cool way to 'see' it, not knowing what was coming up. I can't recommend it for everyone, though. And we did have a GPS line to follow if needed, but I didn't look at it much.
Here was my writeup:
http://www.topofusion.com/diary/2006/08/16/colorado-trail/Of course, to me there's nothing like exploring a route that no one has bikepacked before...