Bread:

Wheatberry or a whole wheat.  Nice and textury.  I don't think 'textury' is a word, but you know what I mean. 

Meat:

None other than mesquite smoked turkey breast freshly sliced by your local deli.  You know what?  Any kind of smoked turkey breast will sell.  Forget the mesquite.  Unless it's available, of course.

Cheese:

Usually, a white cheese will work well with...wait...whoa! What's wappening?!  I'm trying to say that a white cheese, such as swiss, baby swiss, provolone, even some smoked gouda will compliment this sandwich.

Condiments:

Mayonnaise and spicy or dijon mustard, spread on both slices of bread.

Vegetables:

A leaf or two of lettuce, pickle slices (or a pickle spear on the side).  Or more veggies if you prefer; perhaps even tomato slices, if that's your bag.  Or maybe no veggies at all.

Variations:

Grill the sandwich (you know, butter both sides, fry in a pan, flip it over, that sort of thing).  A great idea if you're getting tired of the old 'cold' routine.  Also, using smoked cheddar slices in place of the white cheese is a good idea when grilling, but not as good if served cold.