If you feel your tablet offers you functionality that your phone doesn't in every day life, the question of bringing it on tour comes down to whether or not you want to carry the weight, deal with keeping it charged and keep it from getting broken. The reason not to take it wold be simplicity.
It really comes down to a personal choice. My rule of thumb is to take as few things that need batteries as possible. I've got it down to three: my smart phone, my rechargeable blinky and my basic cycle computer.
But there's no wrong way to do it. You could always mail the tablet home if you decide you didn't want it with you any longer.