Any bread with goat cheese and sliced (soft) pairs - for extra effect, make sure the pears are chilled for clashing temperatures.
Sourdough with Munster and goat cheese - simple, but effective. Kids like this combo a lot.
White bread with apples and cheddar cheese - also good for the simple palette. Use sharp cheddar for extra effect.
Wry bread with avocados and cheddar, mozzarella - great for quessadilla lovers making the transition to grilled cheese.
Gouda with anything.