If you go into it expecting whatever Droid to be an iPhone you'll come away disappointed.  If you go into it looking for a similar device, but with an open mind regarding how it goes getting from A to B you may be pleasantly surprised as I was.  Neither is perfect, if you think the iPhone is perfect for you then there's nothing to be done.  Seeing that you want a bigger screen, I'd suggest taking a long look at the Droid Incredible.  It's not that much bigger than an iPhone, but has a much bigger screen.  The Droid X will feel enormous to you, so I wouldn't recommend even looking there despite the even larger screen.  My wife has the incredible, she loves it.