Do I need a tablet?

So after a year of saving money I was finally able to purchase a laptop. I have been quite happy with the laptop and I am wondering if I need a tablet. I am a large person so carrying around my 17' laptop is not a big issue. Also as I have said before I don't have a real mobile lifestyle. I go work, go home, eat out and sleep. One place I do take my laptop is to my cybercafe I hang out at. I am not a coffee lover so I don't spend much time at Starbucks. I guess the moral of the story is I don't need a tablet but I want one. It is quite difficult to browse the web with at 17' laptop while sitting on my couch. Now the question is which device to buy.