Money talks! With enough budget you can do anything you want. Get some estimates for demo and new installation. Also get references.

Patio doors (plural) seems like they could give a lot of natural light.Another option, most likely cheaper, is a sky light. I can't picture turning a family room into a guest room--seems like you are adding walls, a door etc. Is it worth it to give up the space to a lightly used room?

In this case, the house was built in the 80's and the family room is quite far from the kitchen and the rest of the "living space" so it works to convert. The biggest challenge for me is the fireplace - what to do with the thing that is in the middle of the longest wall of the room?

Is there room opposite the FP for the bed without blocking the doors? I think guests would be pleasantly surprised to find they had a FP. We do better on suggestions with photos.

Honestly post some pictures