I always wonder about these questions and how it all turns out. Lunches differ so much depending upon what part of the country you are in.....
In California, it would be Mexican Food or Sushi.
In PA, what is considered normal fare there?
How formal is your husband's work. How well do you know the boss? Are they big guys and want their red meat or athletes currently in training and want a power lunch? Or they could care less and will eat whatever? Can you order pizza?
We are not big sandwich eaters so I personally would not serve sandwiches, chips and soda to my husband's boss. Unless you have a Foreman type grill for paninis then that would be nice enough. Something with artichokes, or spinach, or arugula.
If you do choose a sandwich, based upon the other recommendations, I would make a Tuna Melt. Make a tuna filling ahead of time. Mix canned tuna with chopped green onion, celery, and mayonaise. Spread on your favorite rustic or whole grain bread or english muffin (DO NOT serve croissants, men usually don't care for them). Layer a slice of favorite cheese (extra sharp cheddar) and broil until melted. Serve with a tossed green salad with avocados, tomatoes, sprouts, carrots, etc. and have a few drink options around.
I don't understand Michelle's issue about making a nice lunch. I love to cook for my husband's colleagues. We are not from the 1920's. There is nothing wrong with supporting your husband if you have the time and desire to. I've had more men ask for my recipes then women and the men have literally told me, "I wish my wife could cook like you." Must be hungry at their home?
Another light fare option is to go mediterranean and serve hummus with pita, olives, feta cheese, type platter. Then make a simple tabouleh salad ahead of time and take out for lunch. Very simple and pleasing.
Hope something works out for you.