There are a number of conflicting articles about how to achieve synchronisation of diaries and contacts between Google and iPad and iPhone devices. I know, because I have been through all the articles. The short answer seems to be that you can use Google Active Synch without needing to plug the iPad into the computer and using iTunes. This article shows how to do it:
This is how I am doing it and it works. Of course, its cunningly labelled in the settings as "Microsoft Exchange" so it would be easy to miss it or not realise it could be used for this. If you are going to do this you will need to turn off the calendar and contacts synch for any Gmail account you have added to the iPad or you could end up with duplicate entries.