I have the S5 and the tab pro 10.1. I'd say that they integrate pretty well, however I think most of it is due to the Google services that I use like play movies, music, Google plus, hangouts, etc
For music I use play music so that I can stream all my music onto my tablet. I also have my music on an SD which is in my tab pro. This is much easier than using iTunes. For messages if you want them to sync across your devices you can use Google keep or S-note. Emails will automatically sync across your devices.
I use an app called side sync which allows you to mirror your phone to your tablet. So you can leave your phone charging and view the screen on your tablet. So you have access to all your apps, messages etc on your tablet. I think if you have an S5 and a tab S got can even answer calls on your tablet.
Samsung have also just announced a new feature called flow which is similar to continuity on ios which allows you to start a task on one device e.g your phone and continue with it on another device e.g tablet or even your TV (Samsung smart tv) .
In terms of good samsung tablets get either the S series or the pro series. If you want the S-pen you can get either the note 10.1 2014 or the note pro 12.1.
Avoid the tab series.
Posted from my S5