Do you really get more work done on a Plus than a 4.7 iPhone? I thought I would too when I got my 6S plus, but I used it in exactly the same way I used my 6. Some things were a bit nicer like browsing the web and reading, but only by a minimal amount. It's not like it's an iPad. I never use landscape mode, so those features didn't end up mattering to me, and really the interface seemed too cramped on the 5.5 in landscape mode to be worthwhile.Honestly, the Plus is beautiful because it's just the right size. Finally, an iOS phone screen that's big enough to really enjoy the interface and get real things done.
I just find some people like the big screen because it's big, and also have a perception the camera is so much better on the plus which really isn't that true with the 7 models. I'll be gladly going back to the 7 from the 6S+, and giving my hands and pockets a break.
If Apple can reduce the footprint of the 5.5 next year, I'll reconsider it. Right now it's too surfboard like.