I macro all dps or enemy targeted spells with a 'target of target' function.
Basically:
/ac 'spell' <t>
/ac 'spell' <tt>

Then I always focus target the boss or prominent enemy, which can also be done by adding it to one of the spell macros.
/focus <tt>

This way, I only ever have to target party members, mainly hard target the tank or main tank, then tab up/down for other party members.
With the option to directly engage enemies still there.

It's not strictly ideal for optimising dps, but for anything outside of savage prog and Ultimate, it's perfect.