Agent69, getting 8gb ram is way more important if you're going to pick one or the other and have that choice. The SSD is on a little card and eventually someone will sell the larger size ones as a part. The RAM on the other hand is soldered on! But i'm sure you already knew this
I'm in no way disagreeing with your post, because RAM can be very useful, but a RAM upgrade isn't always the best option. I own a late 2010 MBA with 2GB of RAM, and it is running strong. If you planned on doing professional work on the machine, I'm sure it would perform poorly. For watching movies, playing video games (portal 2, league of legends), web browsing, and writing, it runs without a hitch. For over 3 1/2 years, those tasks haven't taken up any more RAM, and it is still blazing fast. Most consumers will not use more than 1-2GB of RAM ever, and with the advent of SSDs, paging to RAM is significantly less important than it was with HDDs.
Here is my argument for getting a bigger SSD. The larger the disk size, the faster it performs to a significang degree. You can look up tests on tomshardware or anandtech, but for cost/performance value, 256GB is arguably the sweetspot. Not only will the system run faster in general, but if you do page to the SSD, it will handle it better. For a typical consumer, an SSD is most likely the best upgrade. Sure, the SSD is technically upgradable, but PCIE flash is very expensive, and down the line, external storage is probably a better investment for the hassle and cost of upgrading. As of right now, if you are a consumer and have an SSD based computer on Mavericks, 2GB is the most RAM you will need right now.
If you are a professional user, the sky is the limit for RAM, and I am sure you know what you need for your system. A RAM upgrade could very well be the best upgrade for you. For the average consumer, RAM is no longer the holy grail of computing parts. Especially for mid level GPU/CPU systems, 3-4 years down the line most consumer tasks will be bottlenecked by other parts if you have 4GB of RAM. YMMV, and I'm sure the system you bought will sustain you for many years to come. I used to think RAM was the one and only upgrade until I got a MBA. It is a great computer and I'm sure you will love it.
Matt