I chose the MBP 13" over the Air - Tested both
Interesting - I'm now leaning towards the MBP. I need portability rarely. I might miss the SSD though that's the only thing.
I was in the same situation a couple weeks ago while trying to decide which MBP to buy. Remember, even if you want portability, the MBP 13'' is only a pound heavier and you gain a lot of stuff in that pound. I originally bought the MBA 13" a couple weeks ago, the i5 with 256GB SSD. It was a lot of fun just to be back on a Mac. But then I started to have some serious buyers remorse. I was going to have to get an external HD and probably an external superdrive for CD's/DVD's. I also kept switching the MBA settings to put the resolution at 1280x800 and I felt like I liked it more. When I compared the colors I saw a huge difference, much better on the MBP. The solution was easy. I couldn't believe I spent so much money when the difference was minimal and I could gain so much by switching to the MBP, saving me $400! I decided to switch and it was the best decision ever. I don't feel limited with storage and I've already started loading tons of music and movies on my 500GB hard drive. It's true there is a difference in boot times as well as loading things, but other than that you don't lose a thing. The pro's were far leaning towards the MBP, how often do you boot up your computer honestly? Once you get the programs up and running (not slow, just a few more seconds to load on the classic HDD) the processing power is even more on the pro so I didn't feel like I lost there either. One of the biggest kickers for me was also the option to upgrade later. The MBA offers virtually no upgradeability later on, whereas the MBP you can upgrade flash memory and if I decide I don't need the superdrive in the future I can add an extra SSD in that space. For me it was a no brainer and I haven't looked back once.
Resuming: For me the specs were clearly in favor of the MBP 13"
MBP 13"
-Uprgradeable
-Still portable
-Much crisper screen colors
-Slightly more processing power
-DVD Superdrive (I still love making mixes for people on the go

-The classic style Magsafe (I personally like the design better)
-A proven machine, one that will no doubt last 4+ years easy...they already have!
-More bang for my buck
MBA 13"
-Not upgradeable
-Higher Res screen - more muted colors
-Keyboard slightly less springy - not a huge deal but noticeable
-SSD Flash style memory - much less storage for much more money, very nice to have though - I plan to upgrade my MBP in the future for sure
-Power nap feature in the new Mountain Lion OS available for MBA
-A pound lighter and a cool form factor - I liked that it wasn't as flimsy feeling as it looked - the form factor alone makes it fun
-A great machine, just not for me at this point
I loved both machines, for me needing a great PC for school and as a desktop replacement the MBP had much more bang for my buck. Hope your decision comes as easy as mine, without the buyers remorse part!

