Hi Hugh!
Noting special there with the scales! I guess the Spanish kind of sounds come from the Phrygian scale. Starting from E its E, F, G, A, B, C, D that?s what Stanley and Al is using with RTF from time to time.
I also like to use E major over C#m9 sometimes, just to get a more ?positive? sound. I like the pentatonic scales too and use them quite much but its also nice to improvise with just a simple major scale like E major E, F#, G#, A, B, C# D#...and of course passing tones are always great to use too. In general I do not think too much about scales except if it?s mentioned in a composition! You should ask Jimmy Johnson about the scales he is a master improvisator and knows about those things!
Actually I am working with a jazz trio right now and bass solos on about every song?? that is really challenging ??.to make them say something and make them sound like music!!
But anyway thank you for asking!!
All The Best,
J-O-S