Same here ... about to order the 11.6 MBA and went in for the 13" MBP due to
* 8GB RAM upgrade (only 40 bucks) ... it will do less swaps to the SSD and will improve the life. Also I run VMs so extra RAM is more important than CPU horsepower
* SATA3 SSD upgrade (much faster than air)
* Got a slight headache at the store with the MBA
I ran 2 VMs last night at the same time (Ubuntu / 7) on my stock 4gb machine and all went well, although I had to restrict each machine to 768 megs of RAM.
I'm definitely getting 8 gigs; running my bootcamp partition, Ubuntu, and SL all at the same time will be amazing.