I think when completing the 'from' fields, the 'to' fields should be populated with the same values if not already set. That will make it easier to specify a range.
If the from / to dates are inclusive, this would mean completing just the 'from' (with the 'to' defaulting to the same) would return resources on the specified date only, which mirrors the existing behaviour.
Then I think this could be the default behaviour, because it supports the old method but extends it nicely.
Does anyone have an opinion on this?