Oops, forgot to answer whether there are any SWB/LWB W220's. The answer is "no". In DC's infinite wisdom, the W220 comes in only one standard chassis length (ignoring the Pullman model - which is a "cut-n-stretched" conversion anyway). This was in an effort to cut costs. They did this by reducing the overall length of the LWB W140 while at the same time increasing the rear legroom!
W140 (LWB): Overall - 205.2 inches; rear legroom - 39.6 inches
W140 (SWB): Overall - 201.3 inches; rear legroom - 36.1 inches
W220: Overall length - 203.1 inches; rear legroom - 40.3 inches
Ah, the marvels of modern engineering where less IS more.