It would be nice to have more distinguishing features for upgrades, especially pets. I personally would love to see my SS Wabbit get a little robe, staff, AT LEAST a little crown to distinguish him from the other non-SS Wabbits. I know for me, it is mostly about graphics and how cute something looks that encourages me over the actual stats (yes, I know I am vain). But this could be applied to all pets as well, perhaps a change of hue to their fur when you level them up each 10 levels. I mean something to show you have taken the time (or money) to level them up.
Perhaps AMZ can host a contest for this, and the winner gets a prize for the best artwork/concept (perhaps 100 SS Turnips).