Have been experimenting with an interesting layout (knew this already before but haven't seen some of the nice features on first sight).
* use a whole tone scale
* set all course offsets to 1 semitone (did not find a way to do this with Workbench yet (it seems to use scale steps which is not the desired effect in this case), but "keygroup 1 hey course 2 to 1 semitone set" etc. should do it.
Now going down increases a halftone and going left a semitone. A specific scale or chord can always be played with the same shape and fingering on the Alpha (on Tau you need at least two fingerings). Chord shapes are similar to the horizontal layout with one row offset between fingers - but there are many more possible fingerings in this layout. This variety and symmetry is bought with a smaller range (than with horizontal layout but still slightly more than standard layout) and the fact that chords need more space (than in horizontal layout), so your range between highest and lowest note per hand in a chord is comparable to a piano - not much more than an octave).
Not sure yet how challenging this is to play for nontrivial pieces (you have at least to be able to play a combined "finger beneath" and "finger behind" each other technique for scales). But it's interesting to find unusual chord progressions - and it's very "logical" for both scales and chords.
Range is slightly below 4 octaves (most notes occur 2 or 3 times).
Have fun!
UK
