As other have said, the 13 rMB is probably the way to go. I'm now using a 15 rMBP, which is probably overkill for most needs, but better aligned with my workstation aspirations. I just bought my woman a MacBook, which is good enough for her needs. But her needs are: surfing the web, MS Word, Netflix, and occasionally manipulating photos a bit. No how, no way, would a Macbook suit my needs, except as a semi-tablet. I bought my oldest boys a 13 rMBP, and I'm jealous. It's so much lighter and smaller than my 15 rMBP, and the screen is gorgeous! For 90% of what I do, I can't tell the difference in performance between their 13 rMBP and my 15. I also have a 13 MBA that my work issues me, and I just can't bear the screen on it. I only use it in situations where I absolutely have to be behind the VPN, which are increasingly rare - so it gathers dust.
If the MBA 13 was refreshed with a retina display, it'd certainly be worth a second look. But for now, I think the 13 rMBP is Apple's sweet spot for laptops. Gorgeous display, good horsepower, solid battery life, good ports & connectivity, and good size/weight.
The MacBook is interesting as a second computer. But, frankly, I find the Surface Pro line better-suited for what the MacBook offers in that it's got a lot more horsepower and can also be used as a true tablet. YMMV.