High-fiber cereals - oatmeal, raisin bran, shredded wheat. Fruit goes well with cereals - bananas, berries, apples, oranges, etc.
Sandwiches - toasted whole-wheat or whole-grain bread, lettuce & tomato, your choice of deli meat (sliced chicken, turkey, ham, roast beef). If you pack your sandwiches up high with deli meat, then 1/2 a sandwich will fill you up pretty well and you can have the other 1/2 in a few hours when you get hungry again, without having to make anything in the kitchen.
Wraps - whole-wheat flour burrito tortillas, lite mayo, canned tuna or chicken. Add pickles or whatever else you like if you need to spice it up a bit.
You can make the shopping pretty easy on yourself:
-Whole-wheat/grain bread & Whole-wheat tortilla shells
-Assortment of deli meat * Cans of tuna or chicken
-Lite mayo & Mustard
-Tomato, lettuce (1 head should last you a week), and pickles
-Assortment of cereals (high-fiber stuff or instant oatmeal) & Milk
You'll need a bowl and a spoon for breakfast and some easy-to-peel and eat fruit to help speed things up when you want a quick meal. For sandwiches and wraps you'll want a knife and a spoon, use the spoon to apply mustard & mayo and then slap your ingredients on, then cut with the knife (for wraps, just use the aluminum foil to make a pouch - you can make a bunch at once without them going soggy like sandwiches on bread. The assortment of meat will ensure that you don't get sick of eating the same foods even though it's in sandwich or wrap form.
Also, if you want veggies pick up some bags of the frozen mixed stuff, put in a bowl, add some water, and microwave for a few minutes - this gives you some quick steamed vegetables to add to your diet. I've always eaten like crap when I stay in a hotel or on pretty much any trip and then you end up not feeling too great during your stay and when you get back for a day or two.
One quick shopping trip, a few tools, and spend about 15 minutes every 2 or 3 days prepping food for a few days and you're all set!