Why is everyone here insistent on 16gb RAM? Unless you're doing 3D modelling surely you'll use nowhere near that? I'm waiting on my MacBook as my first ever Mac so maybe it's a form factor thing, but I have a self-built gaming PC at home and 8GB has been fine for me. I'm an ex Intel employee so I'm more of a CPU kinda guy anyway!
For now I don't need it, but I (and I assume many others) plan on keeping this machine for several years. If history is any indicator, RAM requirements for OS and applications will continue to increase as functionality is added.