For debugging, Safari is probably the best - make sure you turn on the Develop menu.
For final testing, use the Apple iOS simulator in the Apple SDK
If you're working off a PC, check out the ibbDemo2 iPhone/iPad emulator in lieu of the Apple iOS simulator
The Android simulator in the Android SDK allows you to simulate virtually any Android device (including tablets) - note that you connect to localhost through a special ip address - http://10.0.2.2 in their emulator resolves to http://localhost on your local machine. Run android.bat in the sdk to configure an emulator profile.