That's the main problem I had with the 6S Plus; it's not really a good phone. It was too annoying to lug around, and the screen size, while nice with some things like texting with two hands or photos, doesn't really stack up with web browsing and the like. If yr out and want to text real quick you need two hands though. Also, I wanted it to replace my iPad, and it definitely failed in that regard.
Then yr back to the two device conundrum- either an iPad or MacBook and an iPhone. They should just make the iPad with a phone app, because if I'm going to carry around a big device, it might as well be my Air 2. Otherwise I was happier with my 5S, and I gave that to my father-in-law. First world problems.