If you can get the same EasyJet fare the next day and you have no pressing need to get to LON ASAP, I'd recommend staying the night in AMS.

There is much more to AMS than the coffee houses and RLD, if that is her concern, and the charm of the city is different during the evening that during the day. In June, the sun will set very late, so too will the evening fun ...

Oh, BTW, has anyone warned you about pickpockets and sneak thieves? I've worked for two large international publishers based in AMS during my life and I am amazed by the number of stories I have heard concerning lost cases, wallets, purses and the like.