I came across Pensato, a new universal iOS app ($3.99) that might be useful or of interest. It focuses on scale relationships and can be adjusted by scale length and filtered by scale type. The price might put you off, but I got it just to play around with. Might be a useful reference, and it’s ability to transpose the scales selected is interesting. Here’s what is basically a tutorial by its developer.
Thanks for this Scott - I’ll check this out: looks like it could be handy for generating melodic ideas and/or reharmonisation. Cheers!