I reckon the RX8 makes a pretty good family car, for example a mum dad and 2 kids sorta family. 4 Comfortable seats, good boot size and a pretty spacious interior. I find the RX8's back seats and general back passenger area extremely comfortable. kids will like the little storage bin in the centre console in back for like lollies etc, and they will also like the overall coolness of the car! Adults will like its comfort, and its kid friendliness
Of course its a bit thirsty, but if you can afford an RX8, then you should be able to afford the bills.