Auto space staves on a page
My suggestions is to have MuseScore automatically adjust the spacing of staves to fill up a page. Perhaps this options could be near "Hide Empty staves" in the Format->Style... dialog box.
Deciding where to place the staves should not be difficult since it's easy math.
M = distance from the bottom of the last staff to the bottom margin.
S = the number of staves - 1 + number systems - 1 (since there are 1 fewer spaces between staves then there are staves and an additional space to consider if there are multiple systems on the page).
d = M/S
Add d to the distance between staves and the distance between systems and they will be proportionately spaced and fill the page.
This feature will make scores with multiple staves look much better and more professional on a page rather than the large space at the bottom of pages we currently get without a lot of manual adjustments.