I think with my DS2 it is also about time for him to drop his daytime sleep. He hasn't had one for about a week and he has been much easier to get to sleep at night. The first couple of days he was horrible in the evening but he has been less ratty without the daytime sleep as time goes on as he is getting better sleep at night.

How are your day sleeps going? DS was being really painful about going down for those too.