Which Mac to consider?

imo, you use very light functions. With that I mean a 5 year old Mac could handle it more than easily (as in your current Macbook).

The base air will be overkill for what you need. You wouldn't need rMBP, not for the performance - but maybe for the screen if that's what you like. But you will sacrifice battery.

I would recommend you boost up to 8gb RAM if you plan to use it for 4-5 years, especially since upgrading RAM is not an option later.
This makes 8gb a no brainer.

i7 is subjective. I didn't get it, even though initially I was convinced on it. Changed my mind after reading anantech's review, and also user's feedback, and especially after discussing with my IT guru friend who said "10-15% performance in the real world means NOTHING, you wouldn't notice it ever".

So yea. Your call on that.

The way I see it, go with i5/8. If you want the performance of i7 - rather than pay $150 on boost 10%, spend the $150 for i7 and $100 for RAM on a rMBP instead.
The performance will definitely be noticeable between Air and rMBP. Though, Haswell rMBP seems like it won't be released till end Sep.

i5 1.3ghz cpu is amazing and it's not the problem. You should always upgrade de RAM first, considering you want to multitask I would recommend doing so. Only if you do video editing you'll be able to notice improvements with i7, that should render a video a few seconds first (20/25%).

I got the i7/8/256 configuration. My thinking was upgrade anything that can't be done later before upgrading stuff that could.

So that meant RAM and CPU before the SSD.

To me, 8GB was a no brainer. So I paid the extra $100 for that. Honestly, in Apple's world $100 for 4GB more is a bargain.

Next, it was between the i5 and the i7. I probably could live with the i5, but I like to use my Macs for as long as possible. And then when they get replaced with a newer Mac, the old ones get repurposed as servers and such. So I've been caught before on the edge of an arbitrary cut-off line for an OS upgrade. For instance, my wife's Macbook is a 2ghz CoreDuo. It's stuck on 10.6.8 ... meaning at some point, the latest iTunes won't run on it. I lucked out in that iTunes 11 runs on Snow Leopard, but I'd bet dollars to donuts that iTunes 12 will require Lion and above.

Therefore, I chose the i7 with the thinking that I'd rather be on the right side of some future update. And it was only $150.

With the SSD, I picked the capacity that I need now. That's 256GB. 128GB would have been too small for my iTunes and iPhoto libraries. The 512GB option was too pricey for me at $300. Besides, I'm banking on OWC releasing an SSD that's compatible with the 2013 MBAs in the next year or so ... hopefully at a lower price with faster speeds and larger capacities.

Voila! Price as configured was $1550.

Yup, get the 8gb of ram. My MBA's are mostly used for web surfing by my family and the 4gb machines will routinely page out and slow down with heavy web usage. Others aren't bothered by this, but 8gb takes care of that problem.

Also, Mavericks memory compression is more hype than fact...

I own the same white 2008 and moved up to the Air 13, 4gb, 128gb. You will be very impressed with the speed difference.

You can make your own call on ram, remember, it's swapping to an SSD if you go through your 4gb which is difficult to do with your needs.