Heather, you being up a good point about seeds not germinating and then causing confusion about which cross they are. I had planned to give mine plenty of room and then yesterday, after listening to a daylily podcast, I was beginning to think 'well, I COULD plant them closer...'
I plan to germinate my seeds indoors and only plant those that sprout anyway, but you reminded me that the main reason I was doing that is that as seedlings grow, you need space between them to know where one starts and another begins.
One tactic I had considered, too, is to plant my (white x white) crosses in between my color crosses so that is an easy (if occasionally imperfect) way of visually keeping crosses separate. Then, I would just have to hope they were actually the crosses I believe them to be and that none were really bee pollinated.