Since no advise offered here, you might try over at the home decoraters forum. I understand there is good design advise there.

When we added on, we had a support column we had to deal with. We decided that to put one on each end of the room to make it look like the two helped support the north wall (but in fact one supports the west wall) This also gave us a space to run our main drain vent without taking up room in the bathroom.

We used wide trim and I painted them with a glazing technique to make them look like marble. The floor is tile so I used colors to match.

The near support column is actually supporting a header for the upper ceiling. In the back you can see the vent pipe.

Turned out pretty neat.

Cathy

Thanks for the advice. Cathy, your photos are attractive.
zinia