With Delta Air Lines, and the Hotel stay is as well included in the price.
Update: This works as starting point from: Boston, Minneapolis, Washington DC, Atlanta (a bit more expensive)
Destinations that we found for this price are: Munich, London, Paris, Warsaw, Munich…
There are for sure other destinations available as well. You may let us know in the comment section, if you like. Maybe you will find an even cheaper combination as well?
How to book this Deal.
Click on Packages, Flight + Hotel, select business class and enter your dates, as shown below.
To get the lowest possible price, you can select the option to make the hotel dates different than the flight dates, the minimum seems to be at least three days in a hotel.
1300$ is the price if you travel as a couple. The price is cheaper for 2 persons as the hotel fare is split across two people.
Here's an example for Paris, this is the price per person in business class and 3 days in a very good Hotel:
Availability seems to be in August 2020 only.
H/T (the part Boston to Warsaw): Flyertalk user alanstar