I have an acquaintance who got an iPad and got rid of his smart phone. He uses the iPad for all things except phone calls and texts to people who don't have iPhones. And honestly, it's not a bad way to go.
I personally like having the iPhone too because if there's an app optimized for both, I only have to pay once. This applies mostly to games, but there are others too. I also like that I can iMessage my wife on her iPod Touch and sync everything to iCloud. Android doesn't really fit in to the way I do things these days.
HOWEVER, you certainly don't have to have an iPhone to enjoy your iPad. Best Buy can suck it.