I'm planning on running the Amsterdam Marathon this year Tom, but was waiting to book accommodation until I know I've got a place in the starting line up (and with that presuming it's not as difficult to secure one as London).
I've done a bit of research though, and a good prospect on the accommodation front (if you check out tripadvisor.co.uk) is the Zandbergen. Looks easily walkable to the start line - but don't book the family room, I've bagsied that for the terrible twosome I will inevitably be bringing with myself and the lovely wife.
I've stayed overnight before races before, but have never done one so large (or indeed a full marathon) so I'm with you on trying to get things as relaxed as possible before hand.
BTW - looks like registration opens tomorrow.
Edited: 01/02/2009 at 20:57