I am trying to get some reasonable maps to play with - I thought CIV IV would generate them randomly like CIV III, but here is what happened to me just now:

I played a game as Isabella for awhile, then tried a new game and got the exact same map, exact same position! Does it not generate a map randomly?

I also find that I am either alone on some continent OR surrounded with everyone next door. It seems far worse than in CIV III. What am I missing? Is the "Continents" map exactly the same every time? Are there no random maps possible?

The maps are relatively random, but a Continents map is likely to be the least random of the bunch, since it pretty much always creates two relatively-equal-sized land masses with 3-4 civs on each.

Try the 1.61 patch's fractal map for more variation.