I went from a 2012 11" MBA to a 2014 15" rMBP and couldn't be happier. But I work from home, and my machine stays on my desk 98% of the time.
Back in 2012, I went for the 11" because I was able to upgrade the processor and get a 256g ssd for what I could afford back then. And, because my machine was on my desk most of the time, it was also attached to my 24" Apple Display. So I didn't really care about its screen.
Fast forward to a couple of weeks ago. My partner took over my 11" MBA so I was on the hunt for a new machine (darn the luck.) This time around, since portability was NOT a factor for me, but power and longevity were, I looked at the MBP line, and was simply blown away by the screen. So much so that in fact, I sold my 24" display to help fund the 15" rMBP. I do not miss my 24" with this beautiful retina screen!
All that jibber jabber, and I'll still say this: if portability were a concern AT ALL to me, I would have gone for the 13" rMBP. I believe it strikes the perfect balance between power and portability, while giving you the beautiful display. I do not regret for a moment this 15" beast, but I'm also thankful I'm not having to lug it around on a daily basis.