I think sectionals work great for families with young children. It looks like your first arrangement would work well. I might swap out the bench for an armchair, though. One thing to keep in mind with reclining sectionals is that coffee tables typically don't work so well with them because of how the foot rest kicks up.

If you opt for two sofas, I'd place one along the wall where your current sofa is and another perpendicular to it and facing the TV. Then perhaps a couple of small scale and low backed swivel chairs before the sliders with a shared side table.

Three sofas might be a bit much.

Depends how do you want your room to be perceived. Let me explain - with the L shape the arrangements works well for a cuddling family, not for the inviting friends (from the entrances these sofa's backs do not look remotely inviting. Works for a TV time with family, but not for the guest gathering/conversation thing. You'll have to take into a consideration how much longer your kids will remain cuddly, because in teens years they are rarely sit shoulder to shoulder.

2 Sofas look nice, but don't do sofa sliders - to be able to have a nicer/bigger coffee table (you would need at least 18" between the sofa's edge and the table, and at least 30" between the window and the back of the sofa), 2 facing sofas are not convenient for the TV viewing - unless if it's a sofa per person and a person is laying down.

Like how the room is claimed with the 2 facing sofas - much less of the unused floor. You'll need a much bigger rug though to ground the furniture arrangement.