I always planned on collecting a few series since
a) I could never single mindedly amass cels from 
only one series unless my goal was to build up 
the "Best" collection of cels from a series - not 
a happenning thing with my limited resources.
b)tastes change - favourites change - new series 
always come along.
c) variety is always fun.

But yes. Utena rocks...... Its been my favourite 
series for a few years now.

Good luck!