Place oven racks in the two center positions and preheat the oven to 350 degrees F. Spray two 17 x 11-inch jelly roll pans with cooking oil spray.
Combine the oil, maple syrup, and brown sugar in a 1-quart microwave-safe bowl. Microwave, uncovered, on high power until the sugar starts to melt, about 3 minutes. Remove the bowl from the microwave oven and whish until any lumps dissolve.
Combine the oats, nuts, wheat germ (if using), and coconut in a 3-quart or larger bowl. Toss to mix well. Pour the syrup mixture over the oat mixture and stir until well mixed. Spread evenly onto the jelly-roll pans.
Place a pan on each oven rack and bake for 10 minutes. Taking note of which pan was on the top rack, remove the pans from the oven, stir the granola, and return it to the oven, rotating each pan to the opposite rack. (If your oven will accommodate the two pans side-by -side on the same rack, it is not necessary to rotate them.) Bake for 8 to 10 minutes, taking care not to let the granola get too brown.
Cool the granola in the pans until it reaches room temperature, about 1 hour. Sprinkle the raisins and dried cranberries (if using) over each pan, dividing them evenly. Stir to mix well. Store in air tight containers, preferably glass jars or tins, for up to 2 weeks.
(You can increase the raisins or cranberries to 2 cups instead of using both ingredients if you prefer. It makes 13 cups total.)