So I'm considering trying cannons on my Excelsior because it's got a decent turn rate. So how do I best put together a cannon build for a cruiser? Should I use SINGLE cannons, so I can still broadside, or should I use dual heavies front and turrets rear?
Cannons excelsior is a great ship! Very possibly the best cruiser the Federation has.
EPTW1 should take care of any power problems you might have running all cannons and turrets.. Cannons sip power compared to beams.
I'd strongly urge you in the direction of Energy Weapon Officers for this ship. One type (the most expensive type, naturally) can reduce the cooldown times on cannon attacks. You can carry CRF2 and APB1, and use your rapid fire basically as often as if you had 2 copies of it.