Well, if you look at it there is a pattern. The early targets often give large benefits and are less likely to resist than say, Poland.
Austria - Smaller country with little resistance to offer, large bonuses and popular support for annexation
Sudetenland - Smaller country which could offer resistance if backed by others, stepping stone for Czechoslovakia and small bonuses, popular support for annexation
Czechoslovakia - Smaller country which has been sold down the river and stripped of many defences, large bonuses
Memel - Very small country with nearly no resistance to offer, small bonuses
Danzig - Slightly smaller country which will resist, offers middling bonuses, would prefer to exterminate completely
The only one that really seems out of place in the order is Memel.