Since the cancelled flight was AMS-PRG wouldn't EC261 come into play?
That's what DL is paying. AMS-PRG is the only affected flighthe as the other flights were US-EU on DL.
AMS-PRG is a Type 1 flight and they were delayed by more than 2 hours, so 250 Euros is due.
Anything additional would have to be either documented expenses or goodwill on behalf of DL - the latter of which wouldn't come as cash.