The first step is to try to keep the grass healthy, or, in other words, put in a little extra effort in the spring to save work over the summer. Start by aerating the grass. You can either do this by stabbing it with a pitchfork at regular intervals, or by pulling out all the dandelions with a weeding fork (actually, pay a nephew to do this). Next, apply a topdressing of topsoil, compost, or manure. Just scatter it over the lawn about 1/4 inch deep. Then scatter some grass seed over the lawn, focussing on any bare patches. The topdressing you applied will feed the grass throughout the summer, but if you feel it needs more, you can use grass seed mixed with fertilizer.
After this initial burst of effort, you may be worn out. If it rains for a week, your work is done. Otherwise, you should probably set a sprinkler to go on every morning so the grass seed will sprout. Now that you have healthy grass, hopefully it will crowd out the worst of the weeds.
Since you no longer have any energy for your lawn, try to refrain from watering or fertilizing it. If you do, it will grow, and then you'll have to mow it. If the grass is reasonably healthy, it will go dormant during dry spells, but it will become green again when it rains. If you can't keep from watering it, do it no more than one hour per week.
At our house, we haven't watered our grass since we reseeded in the spring. Since this has been a drought year, I don't think we've actually cut the grass more than three times. I'll admit that it's a little brown and patchy, but it doesn't look dead. Which brings us to the last way to reduce your workload: reduce your expectations. If you don't mind a little brownness, you can save yourself a lot of trouble!