Had some problems getting my Samsung Galaxy 4 (Google Play edition, GT-I9505G) to connect to a Windows 8 laptop with USB Debugging mode. Couldn't find drivers, etc. Pain in the ass. I fixed it after much effort. Since I didn't find good instructions in searching, posting the solution to help others:
First, enable developer mode on the phone. To do this, go to Settings->About Phone, then tap the Build Number 7 times. This enables the Developer Options menu and lets you turn on USB Debugging and all that.
To get it recognized by Windows 8, do this:
1. Install Kies. Works fine on Windows 8 and you need it for the drivers. Make sure you tell it to install the drivers during the installation, even though it suggests you don't need them: http://www.samsung.com/us/kies/
2. Reboot, then plug in the phone.
If the phone still isn't recognized and shows up in the Device Manager as "Samsung_ANDROID", then do this:
3. Unplug the phone again. Then, on the phone, dial *#0808# to get to the screen that lets you adjust the USB modes directly.
4. Select "AP" and "MTP + ADB" as the settings. Save.
5. Plug the phone in again, and it should find and install the correct drivers.
After this, the phone should be recognized as a Media device (MTP = Media Transfer Protocol) and the USB debugging will work with Chrome (ADB = Android Debug Bridge).