One thing that will make a fun and interesting lunch....once a week be sure to have a picnic! My son is going to be 3 in January and he gets SO EXCITED about picnics. Even if it is in your living room. But when the weather is nice, outdoors is always the best. I have even packed a lunch if we go to the gym and sit in the foyer at the tables and eat...he loves that!
One thing to remember about lunch, it does not have to be a "traditional" lunch! Think of the food groups and go from there. Cheese sticks, carrot sticks, roled up sandwich meath and cheese (my son loves this!), anything that is "mini", the fruit cups, mini bagels, make your own mini pizzas on english muffins (another of all my kids favorites), cheese quesadillas (my son lives on these), smoothies, mini wraps (just make a big one and cut it in smaller pieces (they look like pin wheels)
Hope this helps!
The Original Chef Mama