There is no performance improvement through separating tables and indexes.

A good basic starting point is to arrange objects according to their size. You probably want something like three tablespaces for all your tables and indexes as a starting point ...

i) SMALL, uniform extent size 32kb
ii) MEDIUM, uniform extent size 1Mb
iii) LARGE, uniform extent size 32Mb

You can spread the data files for these over different arrays/controllers, or create one set of tablespaces for each array.
a tablespace for small objects with a uniform extent size somewhere between 16 and 64Kb, then another tablespace for lerger objects with a uniform extent size of 16 or 32-times the size of the small-object TX.