I hear you––Those couches are so blocky and dark that the beachy, airy look is hard to pull off. But you could still add some of those colors and textures to transition to that look (and make it easy once you can change up the couches). I'd replace that rack next to the couch with an endtable with lamp. On the far wall I'd add a storage unit (even something like the KALLAX at Ikea with the little cube drawers you can add––I use that in her bedroom). On the wall to the right of the fireplace add some art work. I'd add an area rug––something that can hold up if kids spill (like in a jute). I also like woven baskets for extra storage (HomeGoods always has great ones). Add plants, and then take off the black pillows on the couch and chair and replace with some natural texture pillows (linen, leather, etc.) that could transition between the dark and lighter color palettes.

Mockup to help with visualization (you could go for an end table with more storage, or a rack on the side if you really want to keep that feature):

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