Wide bench doesn't hit all the tricep heads and will leave you without the horeshoe. Definitely train arms on their own day. If you are doing chest like you should you would only need to do it once or twice a week which leaves plenty of time to do an arm only day. Check out bodybuilding .com for some different ideas and variations. I never believed in changing angles of lifts until I finally opened my mind recently and its paying off big.
I was curling 50# dumbbells for 5x10 (heaviest I have). Dropped to 30# and started doing different angles on the same lifts, wide/narrow grips, also when working arms use a fat grip bar, I put 3" PVC on my bars now. I added just over an inch to my arms in 10 days with some new secret weapons, and I am not new to lifting. My chest and triceps are bigger now then when I was benching 430 a couple years ago, now I am doing 5x10 at 200 wide grip, 150# on close grip varying sets/reps depending on chest/arm day, also on arm day I only lower it 4" or so then back up using a block as a stopping point.