I ordered a 6+ on 9/12 and it wasn't going to be delivered until the end of this week, so on 9/20 I picked up an extra iPhone 6 off contract at the Apple store, and have been using it while I wait for the 6+ to arrive. I did that because my daughter broke her 4s and she needed to take my old 5s.
My 6+ might be here tomorrow (UPS still says 10/2 delivery, which they missed), and I suspect that I'll be keeping both phones and alternating between them. The 6 is an ideal size for a phone, although still not ideal for web browsing when using 52 year old eyes.
At the store the 6+ is much better for full size web pages; but the 6 is much easier for me to use one-handed for phone calls, camera, messaging, email and other frequent tasks like my 5s was. While "Reachability" is a lifesaver on the 6+ it's not a final solution for me to use it one handed. We need a way to "grab, hold, and drag" the screen down, rather than double tapping on the home button. I get credit for that if Apple incorporates it.
The other problem is that most HTML formatted emails still require me to turn the iPhone 6 sideways to read the text and the text is often still too small. It sucks that the iPhone's larger text setting still doesn't affect HTML emails or web pages in Safari. I don't like zoomed mode on the 6 which makes everything big instead of just the few items of text that I want enlarged.
That means those of us with old eyes need more control over text size and word wrap in Safari, period. Since we can't, because Apple hasn't given us the CMD+ feature that we have on the Mac in Safari, that's where the 6+ larger screen comes in. My iPad mini retina is huge vs the 6 or 6+ and I'm hoping the 6+ might be able to replace the iPad, since it's much easier to pack along.
There are other reasons for my wanting the 6+, namely the larger battery so I can really use it hard all day like an iPad, and the optical image stabilization. So, I'll get the 6+ in a day or so, and play with it for 7-14 days, but I doubt I'll be able to convince myself to return it. Friday 10/3 is my last day to return the 6, and I don't think that I can bring myself to do that either.