Nigel and George are hitting nails on the head here - of course any mention of the 303 weakens any chance of agreement, because there are far too many options, far too many varying objections, and no way through the morass of ifs and buts.
The very reason that the 344 was not acted upon was because Stonehenge has been held to ransom by individuals and bodies with a vested interest. The idea of an achievable Stonehenge wrests the power away from these people and summons the application of simple good sense. The term simple and the A303 do not go together, and talk of a wholly unified landscape is just plain silly - the same people would perhaps link Wembley's twin towers with mini-roundabouts in the vicinity.
Lets cut through all this crap and stick with what really is achievable. Get that junction closed, get the tarmac up and the shops out, lay that ingenious recoverable plastic grid car park stuff all over the fields to the north of the plantation and make an access route of it too. Charge to park to recover your money, and pay for the free bus for the disabled. Put a kiosk to sell guides and include a sheet that points people to the two museums. Feel particularly satisfied for the next two decades whilst everyone else continues to argue about piss-pathetic details.
VBB