There are several Earth maps (not scenarios) included with PTW. (Or at least my copy had them.) There's Marla Singer's map and two Kal-El Earth maps (curiously, they have two different versions of the same map...) IIRC, there's a few scenarios on Earth maps...
I personally would recommend Marla Singer's world map, though Yurt's world map is nice (pity there's no PTW version of Yurt's map, though).
I recommend the "TETurkhan test of time start position only" scenario coming with PTW - 256² worldmap with 31 civs and correct starting locations - no special rules - some more units and ressources added, but nothing unbalancing the game imho - provided your computer can handle it - ressource placement is a bit odd in some cases, but all in all, it's great