Seating arrangements - what’s a better seat? Closer to bar/dance floor or closer to bride-groom?

Near the dance floor might be louder. Maybe put groups that are likely to be dancing and drinking near the dance floor, and groups that are more likely to want to sit and quietly converse without as much noise closer to the back near you. I'm not sure if either is objectively "better."

I personally would prefer to sit closer to the bar/dance floor because that is where I'll be all night. My mom would rather sit closer to the bride/groom. It is a know your crowd sort of thing

Agree with this! That will be my plan. Our family and bridal party will be closer to us and the rest in the back. Our venue is long as well but everything is one sided (dance floor and our table at the front). My venue wanted the dance floor in the middle originally and I just didn't like that idea for the space.

As a guest, I prefer to be closer to the bride & groom just because I can see speeches & special dances better!

Family and close friends should always go closest to bride and groom and other guests should fill in the other seats. If I'm close to the bride and groom, I of course prefer to be closer to them so I can see everything well, but if not then I don't mind where I sit.

It depends on the person. Some people would prefer to be close to the bar. I would say family would prefer to be closer to the couple. You will have to go through each guest and decide where you think they will want to be.