We are creating a cross platform game for iOS and Android. We have thought about how and with which services we should integrate achievements and scoreboards with.

For the iOS part, we are pretty sure that this how we want to do, in order from when the user opens the app for the first time:

• Connect with Game Center (Should be automatic, the user shouldn't even notice?) We will also get the players nickname for public scoreboards here.
• Ask if the user wants to connect with Facebook so that we can compare the players highscores with their friends.

We could add Google play game services there as well, but I don't feel like that adds anything to the experience for the end user.

Now comes the tricky part: Android

We thought that we could do just like for iOS, except that we replace Game Center with Google Play Game Services. However, unlike Game Center, Game Services will ask the user to log in to their Google+ account and allow us to access their account. So now, what we have is a double login, first with Google+ and then with Facebook. What will users think about that? Should we scrap Play Services entirely and just ask the user for a nickname within our app and user Facebook for achievements?