Hi @craftingchris I use both Android and iPhone and so use Google quite extensivly and it fits in well on iOS.
Obviously of major importance are contacts and this works perfectly on my iPhone using Google Contacts. Calendar works seamlessly as well including sharing calendars with others.
Because I use a a Mac as my main computer all my notes are stored using Apple Notes but I do have some duplicated on Google Keep and so can say that works just as you would expect on both Android and iOS.
Maps as mentioned 'just works' but I find myself using Apple Maps more now they have improved it and it better integrates into the OS.
Google Play Newsstand I don't use but I can see it is available in the App Store so assume it also works fine - why wouldn't it? I do however use both Google Drive and Photos and can confirm they also work great in iOS just as you would expect them to work backing-up photos etc, in the background or only whilst connected to Wi-Fi if you prefer. You can also have you photos stored on Google Drive show in the Google Photos app if you want.
If you don't get-on with Siri then you can even use Google Now on your iPhone to ask questions.
Hangouts, Translation, Google+, Earth, Docs, Chrome - they're all available to use on iOS and work just as you expect.
Transition to iOS is pretty straightforward these days and there's even an app for that.