Shoujo Kakumei Utena, Code Geass: Hangyaku no Lelouch Recommendations
If your favourite parts of Code Geass are the elite private school hijinks and crazy student council members you will love Utena.
Likewise, Utena fans who enjoyed the series' action sequences and Machiavellian scheming should enjoy Code Geass.
I wonder why no one mentioned the Anthy/C.C. parallel. IMO, C.C. is second to The Rose Bride in rose-briding (and there are even outright visual quotes from Utena lampshading this role of hers). Also, character designs in Utena and CG bear some similarity.