Question #1- Do you think I should wait until I find a wider sideboard for my long tall wall, or does this one works?

In answering this, it would help to know if you plan to keep the piano in its current location.

Can you please post a plan of the entire room, with windows, doorways, which rooms are adjacent, and measurements? That would be helpful, too.

Sideboard size is fine. You just need a very tall piece of art work to go above the size board. That is about the height of the doorway to the right of where the art will be hanging.

Yeah, definitely get a huge piece of art or epic tapestry something. Furniture looks great, but the super high blank wall dwarfs everything. Add a big awesome art and you're golden.

I would not put a piano in a dining room. That does not fit. So I would find another space for the piano. Pianos need to be in a piano room or an over sized entry way or a formal living room or a lounge area. Then I would center the sideboard on the wall with an over sized piece of art above it. And then your chandelier is too high. It needs to hang lower over the table.

Your piano is turned the wrong way around the player should face the room and I find it a bit odd that the piano isin the DR squished into a corner in waht seems to be a large home. As for the buffet it is okay there with the addition of a large piece of fabulous art. The chandeleir needs to be hung much lower and IMO a linear one would be a better choice with that long table.

The piano: first you need the base side facing a solid wall. It doesn’t have to be against the wall (although for sound that would be the ideal), but cornered, with base side correctly positioned, the player would be facing into your room.

What is going on in the rest of the space? What piece of furniture is in the bottom left of your photo?

Why not buy a server and use it behind the sofa (I am assuming that the opposite side of the room is the living area)? And don’t buy another dark piece.

Your lovely room has almost no color. This may sound odd, but a rug in darker and more lively colors would ground this room and harmonize better with your dark floor, and also make the room look less cavernous in spite of the high ceiling. Some tall plants by the windows will also help to make the room dimensions more livable. Find a large painting that also has some warm colors in it to give your scheme more complexity than your monotone decor has now. A dining room should feel warm and welcoming, and a different rug (an Oriental would look great), appropriate painting and plants will accomplish that.

For people who play the piano, do not listen to where you should put a piano. You put it where it goes in your house, so you can play it and enjoy it. That's where it goes. Agree with large art over the side board. Your place is very lovely.

I, strongly, disagree.

You must take care of that baby grand. It cannot go just anywhere…it must be kept away from windows, heating elements, sun…any sunlight. Not only will sun ruin the finish, it also will dry out internal workings.

You own a beautiful piano, it rules the roost, and must be positioned before any other furniture goes into the space.

The sideboard is fine. Your home is stunning.

If the piano is staying, then the sideboard is a good length.

Just a few other suggestions -- lower the art over the fireplace a bit, and carry the blues from the living room side over to the dining room side in the rug.

With ceilings that high (and a wall that wide), I'd look for some kind of fabric art/tapestry to really make a statement.

piano looks like it was sent to the corner for a time out. LOL

Please turn it so the hinge is parallel with the corner and the pianists right shoulder to the room

what a gorgeous home you have ! I could only dream of this...I love the large art idea. Good luck, I am sure it will look amazing :)