I mostly work in scrap/charm projects and often face this sort of dilemma. These are the things I've learned --
Numbering your blocks is key -- but it usually isn't that awful if something happens and they are out of order unless it changes the design. From long habit I number my blocks Alpha across the top and Numbers along the length. If I have a K9 block, there must be dog fabric! I fold typing paper to roughly 1" squares and pin the blocks in the upper left corner with tiny safety pins I got at the dollar store.
You might as well sew whatever comes up together, they end up next to each other in the end. Likewise, there may only be 4 pieces of bright orange in the entire queen sized quilt, but somehow they end up within the same square foot.
Set a time limit. Go ahead and be picky but spend the amount of time you think is reasonable, whether that is 30 minutes or 3 hours. Then go ahead and leave the room/shut the door on the project for at least 2 hours. Come back and see if anything jumps out at you. If not, consider it good enough and done. What I find is that any fiddling you do after you come back only creates more and often worse issues than the "good enough". And once you get away from the quilt for a bit such issues blur into the background. When we are up close and working on the current project it is easy to find every little flaw, but five years from now if anything bothers you at all -- it's likely something you didn't even see during construction. (I've told the story before about my Storm at Sea and how I never noticed one of the large squares was wrong side up until it was completed and hanging in a show. Ten years later and I know it's there somewhere but I have to really look for it.)
I have a small house with little wall and no floor space. I have to layout things on my queen bed which gets challenging on larger quilts.
But I feel the pain, I'm going to be laying out my Post Card quilt which is some 68+ (always make extra) different postcard sized pictures with attic window edges. "Attractive Randomness" is hard to achieve. The statistics student in me says that random can mean that the same fabrics touch or ugly results but the quilter in me insists on the attractive part.