I don't know if this has changed in the last year, but, IME, it doesn't seem to matter which seat you pick when you book your flight, as JQ will reassign all the seats (randomly, it seems) at check in. Be prepared to find out that you've been assigned a window seat way in the back after having chosen an aisle towards the front... To be fair, if you're seated with someone else on the same reservation record, they will keep you together (at least they did with us).