I like corned beef, but it's surprising how little it contributes to a Reuben. Just using rye bread (I used my sourdough whole wheat - close enough), swiss cheese, 1000 island dressing*, and sauerkraut makes a great Reuben. Incidentally vegetarian. A delicious winter lunch.
*I make 1000 island by eyeballing the following: equal parts ketchup and mayo, some chopped pickle or pickle relish, sprinkle paprika