Which day tour or 1-night tour out of Nanjing for 3 business travellers mid-Oct? Yangzhou? by bus?

Instead of bus, I suggest you take a bullet train to Yangzhou for a trip. It only takes 50min. The fare is CNY37.5 for a second class seat and CNY58 for a first class one. Slender West Lake and Ge Garden are recommended to visit. You may also go to Dongguan Street for dining and shopping. The train back to NJ leaves at 22:35, so you can have enough time!

If you are afraid to miss the must-see and wish to make an arranged package, I recommend you turn to Travel China Guide, a worthy and resonable travel agency. Their contact is traveltravelchinaguide.com by the way!