I'm not going to be getting the iPhone 6S series, but will be going for the 7 series. And when I go for the 7 series, I'm getting an iPhone 7+. By then, I really hope they shrink the bezels or something. What they have now works, but it does feel like the phone is more bulky than it should be.
I'm very excited to go for the plus model next. I got the 4.7 inch this time around, but that's because this was my first iPhone (been long involved with iOS, however) and wanted to get something more "familiar". I have tried the 6 plus numerous times and it is surprisingly easy for me to use one-handed. I will keep in mind that it will be more of a challenge, and 2 handed use may be necessary at times. Anyway, I really would love to have the landscape features, as well as the much-improved battery. Oh, and the huge screen of course! Things sometimes feel cramped on my regular 6 even, and using a 6+ feels like a breath of fresh air every time.