I have family that use iPad and an Android phone and a Windows phone. Another uses an iPad and a Nexus 4. We know that the two major ecosystems, Android and iOS, live more happily within their own universe. But there is no need to restrict yourself to a single mobile OS.
Gizmodo has a nice primer on how to use the two devices in harmony. My take away, and my experience, says you’ll have a lot easier time basing your contacts and calendar on GMail. This is because Apple works harder at being restrictive and keeping the deepest integration to themselves. Google tends to want to push their services to any platform.