It depends. Are these spaceships taking off from planets? Because gravity and air resistance would favor the aerodynamic design you see in today's planes and the space shuttle -- less effort, money, and energy involved in achieving flight. And this is off topic, but it reminds me that I saw an electric car recently, looking just like a regular one, but there was no engine under the hood -- just an empty storage space. My guess is the design isn't necessary, but familiar and therefore easier to drive.