I think it all depends on the events going on in those cities. What is your city choice for majority of your itinerary? Don't forget that CDG has one "hidden" flight/day CVG.
All of those cities are usually good for midweek travel that time of year but you need to check event calendars--wine/beer fests, music, arts, etc.
I don't think you'll find significant width differential with Airbus/Boeing coach seats. If you're willing to be flexible, you shouldn't have too much trouble with biz elite for most central EU cities--just a handful of ezeds or paper for Plan B. Don't recall payload issues that time of year, tho. (ATH or MXP?)