I notice you left out MM. WHY?! What you learn as you study Ringo and her compositions are that there really isn't much difference between MM and SS in a purely melodic sense since they were written all about the same time. Here's some patterns I have detected, but you've probably already noticed them if you own her scorebooks or download midi's of hers through google and yahoo.co.jp searches (
).
+ Lots of 7th chords!!! (Perhaps too many.)
+ Complex, brisk melodies. Not many Ringo songs are "sparse", and there are rarely any times where an instrument (including Ringo's voice) is not carrying a catchy riff or melodic line.
+ I'm not totally sure about this, but I think she favors certain chromatic notes; particularly G# (in the C major scale).
+ Pay attention to the bass line. When I mimic a Ringo bass line, I find the whole song comes out more "ringo-like".
+ Her song structure is very consistent through her early works. Later works that experiment more with music of other cultures and genres are noticably less "Ringo-like", but of course are still AMAZING. Don't forget Ringo can write a song every-once-in-a-while that sounds nothing like anything else you've ever heard from her. SG particularly is very free-spirited.
+ Swing. Marunouchi Sadistic wouldn't be nearly as good without it.
The other important thing to consider is that Ringo has sung many wonderful songs she didn't write herself, and I believe you could easily mistake TJ-penned tracks like "Gunjou Biyori" and "Killer Tune" for having been written by Ringo. I'd have even more to say, but I already had to re-write this post once.