Try Wickham Gray HC-171 to create these faint blue/gray walls. For a punch of yellow use accents in Goldfield #292.
This is a great example of a subtle use of gray and yellow. Try Plymouth Gray 1543 & Decatur Buff HC-38.
This is a wonderful bold example of gray and yellow together. Try Kendall Charcoal HC-166 & Firefly #299.
Here is a way to use both the gray and yellow on the walls by creating an accent wall. I'm not really big on accent walls, but certain rooms and situations call for it. Try Revere Pewter HC-172 & Hawthorne Yellow HC-4 to create this look.