So many grays turn blue. after much trial and error for bdrm, bath and water closet , i'm happy with Benjamin Moore Horizon and Behr ultra in Burnished Clay. Neither look great on the card but they dry to a soft neutral gray. worth getting samples to try.

Adding taupe or beige to the walls, in most hues, would blend in too much with the draperies. I love the lavender in the bedding. It would pull the room together if you were to choose a grey paint that had elements of lavender or berry and silver. The color would be subtle, neutral, relaxing as well as refined. This slight shimmer will pull out the subtle nuances in the marble. As the headboard is already so interesting, it would be too busy to add anything too ornate on the wall. To open up the room and increase the light, you could hang a mirror. I would select an Art Deco style with metallic accents to continue pulling together the room. The marble is lovely, but combined with the sleek lines in the bed and bedding it creates a very smooth appearance. To create warmth, it is necessary to add additional texture. I would add a soft, plush or high pile area rug by the bed. How nice would it be to step out of bed on to that?

I'd suggest you have a look through the photos section on Houzz - or there's quite a few good articles on how to decorate :) maybe both you & your wife could save pictures to an ideabook with a few words on what it is you like about each one, and it'll give you more of an idea of what type of things you like? I think colour-wise, turquoise and peach can go together really well - maybe a warm cream colour on the walls & pops of turquoise and peach in the form of throw cushions etc.? Again, just searching on Houzz can give you some great ideas - just literally searching 'turquoise and peach' brings up quite a lot of pictures :) to get you started I've just picked out a few which I personally think work well :)

No experience with babies actually - but seems there are endless combinations - this was just the first / type in and select "Stories" for good articles like this with at least 2 ideas. Many "Photos" on houzz. "Shop" too. [https://www.houzz.com/magazine/guest-picks-desert-beauty-for-the-babys-room-stsetivw-vs~29205805[(https://www.houzz.com/magazine/guest-picks-desert-beauty-for-the-babys-room-stsetivw-vs~29205805)