any time ive chosen other than a parchment color mat, i've gotten tired of the mat and therefore bored with the picture. so go with the least pinkish of the ivory colors in the painting, i'd guess its in the wings.

is there any black in the print? i always like black frames if in doubt. also decide based on other decor where it will hang.

Have you already taken into account the other wood tones in the room and the color on the walls? White would seem maybe too stark I think. If you do have other red toned wood trim and furniture, I would probably go with the expert.

Vintage posters always look stunning framed with a 8-ply mat, which thicker than a normal mat and adds some depth. A black frame would work fine and give the piece a more contemporary look, while a wood tone frame would be more traditional. Consider where it is to be hung and what frame moulding will go with the existing furniture/accessories. Here is example of a vintage poster we framed recently in a 8-ply mat.

Because your poster is so busy (in a good way), I'd opt for a black frame with a double matt. Put a thin black matt around the live area, an ivory matt (close in tone to the beige background in your poster), then the black frame. The black frame will allow your poster to get the attention and not a fussy frame.

Thanks for all the input. To answer some questions:

1. The wood frame the framer suggested is totally plain, no carving, ridges, bevels, or anything of that nature. The wood is a very similar color to the wood of the floor in our room, which is pictured below.

2. She suggested a 2 " mat the same color as the parchment like border around the current edge of the poster. Does that seem skimpy given the size of the print? She wants to have it look like the poster extends to the edge of the frame, so it will essentially read that there is no mat. I wonder if that is the right choice. I think mats help to draw your eye to the artwork. Am I right?

3. It will hang above the black sofa it is resting on in the picture below. There is another black sofa in this room (opposite the wall with the gold mirror). We will hang a more modern black and white print or painting above that sofa. I assume with a black frame. The wall color is a greyish white.

More thoughts on the size mat and color of the mat given this info?

I think when I go and have things framed I listen to the professional which isn't me! Another though might be to have a fil or liner put next to the print instead of a mat?

I think the framer has a really good idea with the wood frame picking up other tones in the picture. You may find that a dark frame is also pretty, but a different wood will make the picture stand out more and make it a lighter experience each time you see it! Your floorboards - do you have any spare? Or you might want to go that sort of tone for the frame. But a mixed tone wood with bits of red would look fantastic. The mat you could go for a vintage piece of velvet if you are going to cover the work with glass. Faded velvet could look pretty. Hope you have fun with all your options!

http://www.allposters.com/-sp/Emprunt-National-1918-Souscrivez-Pour-La-Victoire-Qui-Vient-Pub-Paris-1918-Posters_i12154931_.htm