I would not match the two dining tables......In fact I dont feel that two dining tables are needed as you have a large island that I pressume you will have stools on. To me that is your meals area...but if you want to put a table there then maybe something small say 4-6 seater. There is no point replicating this a few meters down in the dining area so if you are having a proper dining room then you should have a large 8-10 seater I think..which will fit here.....
Everything should look cohesive and complimentary but that is not too say they should "match (be identical in style).......
I think I remember you saying ages ago that there were some pieces of furniture you have already... what are they and maybe some pictures so we can make suggestions that compliment.....
Does Mr Thisisme have some ideas?
I agree with clp.....the family should have a large sectional..... the sitting room is large so that would need to be carefully planned...and you will need maybe two sofas and some nice chairs.... Are you going out and buying all your furniture now......ooo this is the exciting bit...u r almost there.....
Do you have colour scheme.......have you saved any pictures of what sort of style grabs you....., do u have any artwork...? all are important at this stage?