Something like this is what I would hope for:
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Just one example. Kinda similar to the bands style we saw momentarily I think in 17.1. However, it doesn't need to be. The snow mountains could easily be centered on the map with desert edges. Likewise desert could be the center with snow maintains on the edges. Quite a few arrangements are possible. All that matters is that the rules are followed that a biome can only be adjacent to specific biomes (or sub-biomes, whatever you want to call them) for nice transitions.
Again, for the wasteland, I would probably determine their locations after determining city placement. The ground is rubble, so half a city could be in tact, perhaps the most damaged at the edge followed by the wasteland. Or in the center of a large city. Or not at all for most cities.