Hi! My husband and I have been on 4 cruises together and I don't think our room placement had anything to do with our dining room and table location. The other guests at our table had various room types and locations too. The last couple times we've cruised we went with friends so we took up our own table but prior to that we seemed to be seated with other couples around our own age. I don't know if that was coincidence or not. Once when I cruised with a girlfriend, we were placed at a table of single women of various ages (I don't know what that was about!). Most were little old ladies and we were their entertainment (being in our late 20's we were considered the exciting ones).
Often, if your near the front of the ship, you're more apt to get the forward dining room. Aft, the aft dining room. Key there is the word often....as that sometimes doesn't happen. Oh, your cabin category doesn't affect your exact table. Carnival will do its best to seat you with similar ages/"family types". Such as singles/families with children/couples