The room looks pretty full to me.

Are you looking to add more decor items or are you looking to replace some decor (which items?) in the room?

First you need to declutter there is no space for any decorations.

My guess is the vaulted ceiling is frustrating your aesthetic. No matter how full you fill the floor you will always have a sense of open space due to the vault.

The photo looks like you have given the room over to the kids and moved all your furniture up against the walls. Sometimes that is what you have to do for a few years while the kids are younger, but the room will never look designed/decorated with this arrangement.

What do you want to use this room for?

Do you have another living/family room or is this your only space?

Children are main useds. But they don't have play structures. Take out everything like the lounge chairs and small table. A climbing wall with floor pad against the far wall. A start. The height gives you many options for rope bridges and sliding spots. A multi-level soft play frame with slides, a ball pool, I've seen them in malls in Thailand.

Your window treatments are pretty bad. You need new!

Do a better job of displaying the KIMONO.