You know Chris, I've found by talking to others that there are as many approaches to adding data as there are photographers.
For example, when I discussed this with Cory Doctorow, he told me he titles every one of this photos, which I find very impressive. My approach is a little broader. I create lots of custom albums with descriptive titles then let the default image titles stand (e.g. IMG_0018.JPG). I do, however, like to add data in the comments fields for at least a couple photos in each album. I usually do this while the information is still fresh in my mind.
Another thing I do is take pictures of signs, posters, etc., then label them things like "Mission San Rafael Sign" That way I don't have to enter all the text in the sign, but I can quickly find the picture again with the info in the actual shot.
Sometimes I wish I entered more data than I do, but like you, I get caught up in the photos themselves. Any data you can manage to enter though, will reward you some day with a quickly retrieved photo.
If you think of a cool shortcut, be sure to let us know.