I plan my meals out a week in advance every week.
The secret is to plan for extra. Since it's only the two of us I will use recipes that serve multiples of 2. For instance, tonight my husband made turkey tetrazinni which serves 8. Tomorrow for lunch we will have tetrazinni. The other four servings are sitting in the freezer right now for later this week. Since I'm upstate Wednesdays-Fridays I'll pack two of the frozen tetrazinnis for Wednesday and Friday lunch. Tomorrow night we are making the Firecracker Chili (on eTools) which serves 6, I think. Between the tetrazinni and chili my husband will be set while I'm gone. Friday night, when I get home, we'll have a simple chicken salad sandwich and some veg.
If you are worried about becoming bored with the menu (since Mr. K's away for long periods of time), you can work in 2 week freezer cycles. Last week we made lasagna that my husband may eat later this week. You can freeze half for the next week and eat half this week. We freeze each serving in a plastic container (gladware or the like, all ours came with lunch meat). We just nuke it for 2-5 minutes.