First off, I don't mean for pest or disease control. I consider that stuff unreliable at best, and I think diversity in general is the better solution anyway.

I want to know if anyone has suggestions for groupings of 3-5 plants that have worked well for them. I'm particularly interested in guilds for these purposes:

Structural co-support, for instance the classic Three Sisters, corn to support beans and squash as a groundcover. I'm thinking of planting 3 or 4 mounds of Three Sisters on my planting strip along the street.

Natural plant communities, to maybe make the plants feel more at "home"... :-) I plan to group some of my favorite NW natives under a douglas fir: red huckleberry, wood sorrel, and lady fern. Does anyone know of useful plants native to the forests of Kazakhstan to go with my apple?

Aesthetics. Since I am in the city, I want it to look as good as possible. Some that I've liked are bronze fennel with red beebalm and dark red dahlia, and fruit trees with grape hyacinth and early tulips.

Thanks in advance!