I have 3 raised beds in my backyard that I want to maximize use for. Does someone have an approximate calendar (does not have to be perfect) which outlines what activities (growing, harvesting and maintaining) should be during different months of the year and at the same time keeping the raised bed always producing rather than letting it idle. For example, grow root and leafy vegetables between November and February. I realize that there can be many different answers but any suggestions would be helpful. Right now, my main planting and harvesting is spring through fall and rest of the time it is idle or I grow cover crop (fava beans). I live in the San Francisco/Bay Area
Your idea of green manure in winter is a good one, beans help put some nitrogen back into the soil. Otherwise the most simple rule for rotation is to leave it a while between plantings of things in the same family. Some do yearly rotation, some do seasonal. I just have 2 beds for veggies, so my rotation this year looks something like this, I've also included a couple of the companion plants I've used.
Summer - Nightshades (Tomato,Peppers) + Basil
Autumn - Brassicas + Sage
Winter - Beans
Spring - Apiaceae + Onions
Summer - 3 Sisters - Corn, Beans, Squash.
Autumn - Apiaceae + Onions
Winter - Asian Greens (Small quick growing brassicas) + Sage.
Spring - Asters - Lettuces + Jerusalem Artichokes (which I've heard also fix nitrogen)
And then the next year I would swap the beds.
Here's a short guide from Gardening Australia: http://www.abc.net.au/gardening/vegieguide/crop_rotation.htm
As you say, planting calendars are highly localised as even in a smallish area there may exist microclimates. What you are looking for in San Francisco can be found here http://smsf-mastergardeners.ucanr.edu/Vegetable_Schedule_for_San_Francisco_-_San_Mateo_Counties/
I use this one for NZ http://www.gardengrow.co.nz/ so everyone needs to search for the one that suits their location, either online or in books.