There is nothing wrong with mixing wood and painted pieces in a home or even in the same room. The black set looks better suited to the architecture of the home and is more of a 'classic'. The wood set is very Contemporary and unless you absolutely love, love, love it, it will seem very 'dated' and oh so 2009-ish in a few years. What you choose for the dining room will also depend on the style of the other furniture in the house not just whether they are black or wood.

Please post pix of all 4 walls. Consider a reversible chaise sofa for a sectional feel and some built-in flexibility. Think about credenzas and lamps flanking the FP.

A couple of things strike me right away that throw the room off. First is the rug: It needs to be much much larger, and it should never be narrower than the couch. Second is to get longer curtains and hang them about a foot higher than they currently are. The art arrangement over the piano doesn't work; we'll remedy that. I like your fireplace and built ins. The shelves just need to be better styled--there are some good articles on Houzz to help with that, but basic rule is 1/3 books. 1/3 objects. 1/3 empty space--and I'd remove everything now over the mantel and use art. I suspect you can buy new furniture for no more than what it would cost to upholster yours, but that's a decision for you to make. I'll return later with a rendering of your room.

agree about the tv. man oh man is that thing high. anywhere else you can put it for staging? and your pictures are also hung too high. But if selling, you should remove all family photos and store them. this is just weird. Too many chairs, too far back. Keep maybe the one red chair in the corner by the window/fireplace. remove the other chairs. you need a sofa and one, maybe two chairs when staging. get a new fan,,,like this one. the one you have is way too small and is meant for a very small (like 8x10) room. whatever those yellow bulbs are, replace them w/daylight bulbs. you don't want yellow light. Let the fireplace be the focal point. (without that tv hung to the ceiling! get a nice piece of artwork) similar colors to yours. get a picture like this above the fireplace. and don't hang it too high! from the floor to the CENTER of the art should be 56-60". eye level for average people. they have a lot of books and stuff, so I wouldn't copy that. but the smaller chairs are nice, and the little pillows are nice. sofa, coffee table and a chair,,,nice rug. that's all you need in there. sofa, (this is a sectional) ottoman, and ONE of these chairs,,,facing the fireplace. (see where this tv is above the box?? that's how it should be) or this one (notice the tv) Sofa, one chair in the corner. you can place the sofa under the window, or float it about 10' back from the fireplace. notice the rug. get something w/some interest or do a sisal rug. nice chandelier, coffee table. you could place a larger sofa like this under your window and have the two chairs directly across from it. Like shown here. pretend this is your fireplace. set up furniture just like this. get a nice light or a better fan. done. another visual. one more. see the diff between all of these and what you have? The dining area looks nice.