I'm in the process of working with my architect to design a simple 4 bedroom bungalow and I need the inputs of the esteemed members of this community. I want to have an open plan living area that combines the living and dining rooms and the kitchen, and I don't want there to be any pillars. This living area will be 32ft long by 28ft wide

My architect is insisting that there must be at least one row of pillars in the middle as well as along the perimeter walls to make up for the reduced walls. I'm fine with pillars in the perimeter walls since they will be hidden but I don't want any pillars in my living room. So what are the most structurally sound and economical options?

So far we have these choices
1. Use thicker roof joists and have a normal wood frame roof
2. Use concrete beams to span the width of the house and mount a normal wood frame roof
3. Use a steel frame roof

Please can you advise me on the best option and what dimensions to use. Thanks a lot in advance. Below is the sketch I gave my architect