Most Helpful Girl
Hug her. When she's just rushing around dealing with the kids dinner or getting them ready to go out, stop her and give her a hug.
When you notice things that make you glad she's the mother of your kids, tell her later on when you get a quiet moment together. Tell her what you appreciate about her.
When she looks nice, tell her. When she makes an effort to look nice for you, tell her. When she looks tired, tell her she still looks good lol.
Really though, it sounds like you're quite nice to her already. Sounds like you do lots to help the household overall and pull your weight. I know things change when you have kids, you just don't get as much time together, but just take a little time out together each day even if it's just a quick coffee together before the kids wake up.