Drawing, please. Is this a flat ceiling or a cathedral ceiling. If the latter, are the 3 beams parallel or perpendicular to the ridge? How high are the beams (against the ceiling or lower)?

The Aug 2016 issue of This Old House has an article titled: All About Ceiling Fans.

1'6" min distance from wall or sloped ceiling. 7'-10' minimum distance from floor. Steer clear of (existing) lights, rotating blades below a light may create a flickering effect.

Occupied space (in sq ft) / 4 = blade span in inches, wider if ceilings are high.

DC motors save up to 70% on electricity.

Higher cfm fans provide a better breeze, usually have more robust motors that will last longer and run quieter.

does it make sense to put 2 fans instead of just 1?

Do you have wiring in (or on top of) the beams?

right now the wiring comes along the beam, where the current fan is. I can do the same for the other, or put it in the wall.

Actually you want fans blowing UP in the winter to keep the air from layering at the peak. Mixing it with cooler low level air.

Two would be better than one, just for mixing purposes, in a room that big.