It depends on which stage your start-up is currently at. Could you share a bit more info?

The key thing to ask is "which idea is going to create the biggest impact?" There are plenty of ideas that may be "cool" but ultimately nobody really needs it so it probably won't have an impact. Segways for example fall into this category (though they are experiencing some success in the tourism industry). On the other hand there are some ideas that would appear to be pretty mundane and boring, but they fulfil a real need and end up becoming a great success. The paper clip is probably a really simple example of this. Go out there and find out who the idea will benefit, speak to them and find out if it is really something that they need. Good luck :-) Hiong