In an upcoming Europe trip I have the opportunity for a days stopover in either Salzburg or Vienna, but not both. Which should I pick? I've effectively got a bit under 24 hours in the city: arriving late morning, leaving early morning the next day. Salzburg seems more "picture postcard" and with everything condensed into easy walking distance, Vienna more "classic Europe" but with the sights spread out over a greater area. Pros and cons please? "Both" is not an option.