Fool-proof is asking a lot. iWeb takes away a lot of control from the user so I guess it might qualify in a way. Web design in itself is rather open-ended so fool-proofing it is next to impossible without taking away a lot of control from the user.
If you're not too much of a fool though (😉) to can look at DreamWeaver, RapidWeaver, KompoZer, and ones listed in the stickies.