coffee(table) and a stack of books

Sometimes arrangements take a long time to get right.  For me this is particularly true of tabletop arrangements.  I can shuffle furniture all day long and find several configurations I like, but give me small items for a tablescape and I struggle.

Look One for my coffee table partnered moss and a stack of books in the room's colors.  (Note: the mismatched wood tones are both destined for makeovers--paint for the table and mosaic for the mirror/tray.  Not necessarily soon, but soonish.)

As I sought resting places for other items, I changed the layout a bit.  Look Two incorporated the beloved spring and a cake stand I stored on top of the kitchen cupboards in our last place.

Here the "space" between the tops of the cupboards and the ceiling is walled in.  On the plus side, I won't have to scrub greasy dust off my cake stands every time I want to use them now....  (Please tell me I'm not the only one whose cupboard-top items always get gross.)

I liked this view from the couch, but from every other angle it was just weird.  I think it was the bookends.  Maybe I had too many books out?  Or it could have been the heaviness of the book/spring end imbalanced with the airy effect of glass-on-glass at the other end.  Then again, my refusal to center the tray could have had something to do with it.  Shall I include an "all of the above" option?

As it stands now, Look Three:

I tried to counteract the glassy end with the weight of those same books, though some went back on the shelf; it really was too big a stack for the table, I think.  I set the spring at an angle to avoid making the look too formal when I caved and centered the tray.  It doesn't always work, but I like to try things off-center or at an angle before I try them centered and straight.  I think it's because I like even planned-out groupings to have the effect that they just fell together.  I want people to feel comfortable in my space, and having everything "just so" seems counter to that goal.

Do you have any methods for making your fully-planned arrangements look accidental or, if you prefer, serendipitous?  What mood do you go for in your rooms?  Do you put your feet on your coffee table?  Does your company?  To me that's a sure indicator that a guest feels relaxed.