I think it's perfectly fine as long as you put some of the color in the room too via accessories. My bedroom has apricot walls, white wood work and all the rest is cream and it's yummy. Do what you love, that's all that matters.

My fireplaces are all different than the wood trim (oak verses cherry and mahogany).

I think it's important that you are sure to keep the colors separated a bit. I'd be worried that a cream next to a white might just look like bad lighting or a dirty area (depends on the white and the cream). I think a tan would be a better choice than a creamy tone next to the white...just to get that definate differentiation of tones (that's not a word...I'm tired and refuse to look it up) :oP

Good point to keep the color separated. With a tan or taupe color pulled from the rug, the fireplace/bookcase will appear as a piece of painted furniture and should unify the look. Now all I have to do is find the right tan/taupe color.

Here's what we did:

(Not that it's right or wrong, or you'll like it or not, but at least it's a visual example.) We had painted all our trim Super White glossy and all our walls and ceilings Elmira White eggshell. We considered dark wood for the mantel, then decided to blend things in and just used dark wood for the counter on the shelves. Everything else in the fp and built-ins was painted Elmira White in a glossy finish, even the crown molding and the small amount of baseboard at the bottom of the mantel. But the baseboard under the shelves, still white.

And I'm going downstairs right now to straighten up all those cords, lol.

Thanks for the visual Seg..Our situation is similar. Good choice with the egg shell, as the super white would have way to bright for all the shelving (which is what I am also trying to avoid).