Ideally allow at least 3 feet for each chair (2' chair depth + 1' to get in and out). So if you have a 12' space, 6' might be taken up by chairs. That means you can fit a 72" round but wouldn't have a lot of extra space. The leaf would make it really tight. I'm all for extra space, but I fell in love with a round table, so I will deal. I have an 8x8 space plus walk room on one side, and I picked out a 48" round table. I have no extra room on some sides but the roundness helps. There are a lot of options. I would go into a showroom and ask the sales associate for help. There are convertible tables, thin pedestals, variable tabletops, exterior and interior legs, 3 legged tables in addition to leafs. Sorry that was probably not much help. I went into a crate and barrel showroom and asked for help and I was able to figure out what I wanted through the process of elimination. They have enough different configurations that you can get an idea of what will and will not work in your space. I would optimize floor space for your family and only add the extra tabletop space when you absolutely have to. The chairs make a big difference in how much space you have around the table when not in use. You can choose uncomfortable chairs that fit tightly against the table (if the table allows) or comfy upholstered chairs that take up more space when pushed in as much as possible. If you go rectangular, you have the option of benches. They have upholstered benches too. Every inch matters. If you can trim a few inches off the chairs or table edges or scooch the chair under the table a bit more, you may be able to come up with another 6-8" around the table. This one says it will fit 6-8, but I wonder if you could get more kids around it if you use benches. (It's not the most attractive IMO.) Table goes from 34x57 to 57x68.

I would recommend either a solid color fabric, or a very soft, subtle pattern (almost tone on tone). The fabric on the chair seats and the chair backs already have quite a bit of detail, and the wood shutters bring in some texture as well, so I think your drapes should create a simple but elegant backdrop. My favorite look for drapes are ones that are fairly close to the wall color, (could be a tone or two lighter or darker) and that are hung from as close to the ceiling as possible, ending just above the floor (floor length, but not puddled). If you have enough room on both sides of your windows, extend the rod past the width of the windows by about 10-12", so that when the drapes are open, they can hang straight down with the inner edge just meeting the window, and not actually covering it. I personally love linen drapes, but if you want a little more bling, consider an edging like a Greek key in gold, or a silk drape that has some sheen). Double or triple the panels on each side, for a full look. Here are a few looks to consider. Going with a higher contrast drape, like a blue or green from your chair fabric or art, could look quite good too, but I'd still stick with a more solid color look. Please keep us updated with what you decide to do. :-)

10x14 rug marked

Ideally, your dining room rug should be about four feet longer and wider than your table. You need 18 to 24 inches on each side so you and your guests can slide chairs out without worrying about falling off the edge of the rug.