So there’s a lot I could say about how to set up your family room, but it would be way too much detail! The first thought I had would be to remove the 3’-10” wall. There’s so much more you can do with the space with that gone. Most of my ideas hinge on that. I did a couple with the wall intact. A few basics when doing a seating area is that you want your seating to be no more than 6 ft from each other for having a conversation. An area rug is really helpful in anchoring the area to be used for furniture placement. Yes, a sectional will give you the most seating but because the room is narrow, it could make the room feel closed in. What can help is having legs and sticking with something more tailored and not overstuffed. If you go more modern, sectionals tend to be very deep and it could end up swamping the room. I recommend using painters tape and outlining it on the floor and get dimensions before you set foot in a showroom. I would take your tv out of the corner and get it up on the wall. You can put it on an arm and angle it toward your seating area. Unfortunately, when I post these they may not be in order where the floor plan matches the 3D elevation.

More pics

More pics

Wow! Thank you so much! The TV will definitely be going on that wall. Unfortunately the 3'10" wall has to stay. I actually kind of like the idea of the smaller "L" shaped sectional and maybe one chair. I'm struggling a bit with how to determine the appropriate size. I agree with having the bottom "open" with legs will help, but how can I make sure it doesn't feel like it's taking over the room. I'll be using the tape marker on the floor for sure which will help, but I'm still nervous it will look like it's consuming too much space. Any tips?

So here’s a pretty good article on measuring: https://www.wayfair.com/sca/ideas-and-advice/guides/how-to-measure-for-a-sectional-sofa-T1275
A couple things to keep in mind are keeping the sofa away from the windows to allow for drapery and/or heating vents as that distance will add to the overall depth measurement. You want to make sure you allow 3 ft for between the end of the sofa and any walkway or other furniture. Definitely take advantage of the free design service that most stores and online stores offer. From a design standpoint, I would try to center the sections on the window locations and also allow for any end tables you may need. So if you look at the layout I did with the sectional and the 3’-10” wall, that section has four seat sections. I did that so that it would be centered on the window. The sectional is 11’ x 9’ x 3’ outside dimensions. Hope that makes sense. Good luck!