The following is a LIVE editable, spreadsheet that you can use to consider descent times and distances when comparing descent rate and speed.
This will that allow you to calculate descent considerations that are outside the traditional 500 and 1000 FPM descent rates or for different ground speeds. Play with this a little to get a feel for results of different combinations specific to the aircraft you fly.
Note, since this is a live sheet, if multiple people are attempting to access the file at the the same time, you could end up changing numbers at the same time. Sorry for that, but at the moment, this was the quickest way I could put this up on the website as an example or for planning purposes.
Second Note, unfortunately this tool does not work on an iPad.