what a lovely space. i'd work extra hard to have the floor leveled to do tile, esp. with the nice arched openings. you'd enjoy potted plants a lot more if you didnt worry about dribbles. you should get an estimate if you havent.

I think I would add some wood wainscoting to the lower part(36" up from floor) of the brick columns to add some depth and interest. and then maybe use a nice engineered floating floor on top of the concrete. That would be much warmer floor to spend time on then a tile floor.

I would patch the cracks in the floor and paint it. I'd then purchase an indoor outdoor patterned area rug and place it over the painted floor to add some pizzazz to this lovely sunroom.

I recommend that you speak to a tile expert about leveling the floor and then tile it. You can always put down an area rug, but for a sunroom, tile is the way to go.