Never really saw the appeal of having a cluttered exterior and won't be any help in that regard, though I do like creating pathways and different angles by utilizing hedges and flowers. I hate squeezing by a bunch of plum spaced stuff just to get from point A to point B in RL, so it just bleeds over into the game, haha....
I think your lot is just fine without adding anything extra, in a way it allows the design to speak for itself. But if you must, maybe placing a medium sized shrub around the sides or a couple flower beds and stones around the pond. The seating area is nice and would be enough for me.