I rotate my beds never growing the same plants consecutively. Not sure, but is it 2-3 years before one can replant in a prior bed?
The old rule of thumb I'm familiar with is a 4-year rotation of Legumes > Leaves (i.e., Brassicas) > Fruits (Tomatoes, Squash, etc.) > Roots. Now, within my home garden I definitely don't grow an even enough assortment from each of these categories to be able to do this, nor is my garden large enough to do a strict rotation like this. Since I keep my vegetable garden organic, I'm mainly concerned with soil nutrients and pest control. I try to follow legumes with veggies that can use the extra nutrients (brassicas or corn, generally), and I try not to plant veggies that get hit by the same problem insects following each other. If I can keep my rotation to at least 3 years, then that's good enough for me.