I used to really enjoy one-hour decs.
As I remember it, the 1500 was started exactly one hour after the 100 m (I remember one Athlete coming a little late, but the time was running, when he started his race. According to Janek he should have been disqualified - so I'm not sure about this).
It's most fun, if you build pairs of Athletes with similar profiles (they can stay together, but they don't have to). Key for the athletes is to be able to get easily from event to event in order to have enough time after the 400m. It's great if you offer a little cart for the athletes in order to change shoes while changing places.
You also should have a good speaker, if this is done well, you can create an amazing atmosphere during a one hour dec.
In the US, the switched the events around; I don`t believe, it helps much and it definitely tkes away from the nature of the decathlon.