I think you may be surprised to find such a cruise can cost even more than $10,000 per person - depending on the length and stateroom category.
You indicate you want at least 300 sq ft. That is just over the everage minimum category for cruise lines like Silversea, Seabourn and Regent.
I would recommend Silversea although I am not entirely sure of the smoking practices. With a mostly Italian navogational staff and headquarters in Monaco - they tend to have a more European view on smoking, although I am fairly sure you would not find it a problem the vasy majority of the time, you may have to walk through a smoky room once in awhile.
I have to add Crystal, of course, and the top tier of Cunard. These are bigger shgips and will have more of the lectures and concerts that you crave. But they tend not to spend quite as much time in port - depending (again) on where you are cruising. In Europe and other destinations of interest the lines schedule many more port stops, but I took a trans-canal cruise on Crystal and in 16 days we only took one tour out of three port stops. The funny thing is that we didnt care.
All of the luxury cruise lines are selling with tons of incentives, including credit for shore excursions.
I have had incredible shore excursions on Silverseas - including overnight hotel stays in Luxor Egypt and Cairo, for example.
I haven't yet tried Seabourn and I have not sailed on Regent on over a decade, so I can't say much about those.