I'm a little confused by your post, but I think you're asking for a cleaner, brighter white for trim and built-ins? How about Benjamin Moore's Super White? If you're also looking for a creamy white for walls (?) Ben Moore's Linen White is a winner, imo. It will contrast with your trim, but feels clean and crisp. I don't think you can go wrong with it. Hope this helps.

As for your fireplace, stain vs. paint, I'd paint it to match your trim.

I would consider doing the fireplace area a different shade of white other than the door & window trim. I think that would give it a more 'collected over time' look. I believe in the power of "3's" or 'odds' so I would do the built in's the same as the trim.

Stain or paint the mantle? Do you have other stained pieces? If not then I would paint it.

oh i really do want the room to look 'collected over time' (it is anyway,lol), so thanks for putting that into words for me.
the walls are ben moore rosemary sprig (which we like)and the trim is non-descript off white with no gloss to it and i'm not really sure if that's where the glossy finish should be anyway. i think i'll leave the trim alone until the fireplace and built-ins are done.
so i want to brighten up somewhere, and am unsure if it should be a glossy cream brick fireplace, and/or the built-ins and/or the trim or two or three different shades even.
therefore i think i'll start with the brand newly built faux brick fireplace, since that's a huge gorgeous feature in the room. i'll take pics as soon as possible, i promise! it's sort of modeled after lavender lass's rustic romantic idea.
i know i want it to be creamy and elegant enough to wow the room.
options include bm mascarpone and linen.
which is best to work with golds,pinks and greens?
fireplace mantle would be the only painted wood in the room, today i'm leaning towards a dark walnut stain.
i can wait on the built-ins,they're not even built yet.
i can't wait to go to the paint store now, thanks!