I wonder first what you do in the bonus room, which would be a great craft room. The breakfast room is too small to seat more than a normal family, so where do you plan to seat guests for Thanksgiving? The great room isn't large enough to include a dining area, especially with seating at the proposed island. In such a large home with four bedrooms, I would expect to find a real dining room, though the shape as pictured is a bit weird for furniture placement. If you wall off that space, returning it to a dining room function would be difficult without removing the new walls. Also, by opening the kitchen to the great room, you put your kitchen on full display at all times, even when messy, unless you have a live-in maid to keep it neat or you only do takeout.

Bonus room would be great office or craft room but we desire living all on one level that we use daily. We presently have stairs and we are able to climb so maybe I should return to thinking about it. When, and if, the time arrives to not use stairs, I guess I deal with it then or maybe I am not needing my sewing/craft room.
We have had formal dining rooms and while great for Thanksgiving and Christmas Eve, we are not interested in having a room to use only a handful of times a year.

Consider removing the small closet in the corner of the kitchen and putting the fridge there to make the kitchen more open. Are the plans your existing building? If you recess the beam between the kitchen and great room that would also make it feel more open. Depending on how it is built it may also be possible to remove the columns at each end of the counter.

This is one of the plans we are considering so there is time to consider the placement of beam, etc.
Thank you so very much for your input!

Perhaps doing double pocket doors or French doors on the dining room instead of walls makes it a more convertible space. You could hang sheets on the doors (or blinds) to keep craft clutter hidden.