There were times when I had several parallel datum planes that I related to sketch curves (lines)
so it could easily be seen what the dimension to each datum plane was.
If I have time I will post a sample NX file.
As mentioned above there are times when I like relating my datum planes to a sketch line so the dimension to them are clearer.
The sketch and its dimensioning can be created to make the datums equally spaced or not.
I attached a simple file to demonstrate it.