Another theme common in Asia is the Luck (Blessing), Wealth, and Longevity where 3 different kind of trees representing each of the group are grouped together or the trunk developed to be gnarly to show longevity, the ramification of the branches developed to show vast wealth, and the apex developed to show flowers/fruits as blessings/luck.
Yet another common one is the Four season where flowering trees are grouped with flowers for each season.
And there is the one for the Five Elements of Metal, Wood, Water, Fire, and Earth arranged in a way that shows an unending circle etc..
And then there are esoteric named themes such as Dragon rests in clouds, Tiger hides in thicket, Toad croaking for rain etc..
Once again, for me now I will be happy to learn to graft, propagate, prune branches and roots, trunk development, root development etc.. My focus is all in the basic stuff. It is fascinating that my interest in bonsai actually helps me be a better gardener. I now think nothing of grabbing a branch of pear and graft it on another pear tree just for kick. When I need another pomegranate, it's nothing now to take cuttings and stick them in pot and plant them later. I really like air layering. It takes just a few minutes to do one and it's practically guaranteed I'll have a viable tree to plant later. The trees I have in my yard have even been pruned for better ramification etc.. This spring I'm going to do a couple through grafts on my pear trees just because I want to practice