I'm planning out our garden for next year, and I'm looking for advice on planning crop groupings and rotations for subsequent years.  The garden as a whole is intended as a combination market garden and kitchen garden.  Total area is approximately 1/2 acre, to be divided into four sections.  My current thoughts are as follows, by section:

1 -- Potatoes interseeded with alyssum and buckwheat as cover/weed suppression, and nasturtiums for pest control.  Tomatoes (single row per bed, supported by posts and twine) interseeded with carrots, basil, and borage.

2 -- Garlic (planted the fall prior), followed by late salad greens and fall beans.  Onions interseeded with parsnips.  Bush beans interplanted with marigolds, with beets seeded along the edges of the bean rows.

3 -- Okra and sunflowers, interplanted with melons/cantaloupes and vining peas in a sort of 3 Sisters thing.  Sweet potatoes.  Cabbage, kale, collards, and chard.  Radishes and turnips, scattered, for weed suppression but harvested too.

4 -- Fallow and cover.  Probably a small grain, to be harvested and the straw spread back on the ground. Will likely incorporate chickens and/or ducks to clean up grains, scratch around, eat weed growth, and fertilize.

In what order would you rotate those four areas?  What should follow what, and what should NOT follow what?  Would you make any major changes to any of the combinations, and if so why?

We've got one garden bed where we're doing the corn and melon combo this year. We're planting them to follow the peas because in our climate the peas start dying from heat stress at about the same time we plant corn and melons.

I tried the same thing last year with corn, water melons and long beans. It's going to take more tweeking to get working properly because this combination was not a success. The corn finished before the beans took off and the water melons never did anything. We planted in spring and by late November the only surviving water melon vine was about two feet long and had never flowered. Part of this was that we went on a long vacation at the worst time of the year and so left all the plants. The corn was done by then, but we could have done better with both the beans and the water melon, I think.

In my experience borage is a huge plant that doesn't necessarily play well with others. I'd worry about carrots and basil having enough room to thrive.

Most companion planting resources say that beans and all alliums are mutually combative.

There are a lot of stories that suggest that sunflowers can also be a problem with other plants. I know from my own experience that it's a bug magnet, which can be good for attracting beneficial insects but its also often covered in pests. While that makes it a good trap plant you might want to keep it to the side of other plantings. At one point or another I read something that suggested it was used with the tradition three sisters garden by planting it at the perimeter of the gardening spaces. Pests hopefully stopped at the sunflower before decimating the other plants.

Edit:  I just want to acknowledge that I'm kind of hazy in my understanding of rotation and polyculture. I tend to just try to intermingle as many different types as possible. So far, so good, but I don't know how long it would take to make any shortcomings in this technique apparent.