Rotation, Rotation

I have written about rotation in the garden in the past.  The most ambitious rotation scheme I have seen (and never been able to emulate) was in Mother Earth News, Feb 2010.  They list nine main groups of plants to include in the scheme.  The nine groups are the:
Onion family: Onions, leeks, shallots, garlic, chives.
Carrot Family: Carrot, celery, parsnip and parsley.
Sunflower Family: Sunflowers, lettuce and a few other leafy greens.
Cabbage Family: Cabbage, broccoli, kale and some other leafy greens, Brussels sprouts, kohlrabi, and rutabaga.
Spinach: Spinach, beets, and chard.
Cucumber: Cucumbers, melons, squash and gourds.
Pea Family: Peas and beans.
Tomato Family: Tomatoes, eggplant, peppers, and potatoes.
Grass Family: Corn, wheat, oats and rye.

The idea is that rotating these crops has two important effects. First, disease and pest burdens are thought to be lower if the groups of plants are moved from site to site. Second, some crops may selectively "drain" the soil of one or a few nutrients. Rotation gives the soil time to recover.  However, most of us have limited space. Over time, an ambitious rotation system might break down (without careful planning), esp.as  that rotation should be on a 4 year schedule (that is, members of the same family of plants should only be grown in the same bed only every 4 years, though some recommend 5).
What do I do?  My best.  I have three distinct vegetable garden areas and divide the large one into two. I try to rotate across these,  My problem is that I grow a lot of members of the tomato family (none of the grass family) and a smattering of all the other groups.  This means I I need a larger area for this one family, smaller areas for the others, but this does not easily work out in a rotation scheme.
Happy gardening!  Try some rotation!