Hi --
I know you'll want to hear from Cathe too, but in the meantime, here's my .02:
What REALLY worked for me was in addition to heavier weights, lower rep exercises was incorporating some pull ups. If you have access to a pullup bar, I'd highly recommend doing a set or two. If you do wide grip pullups, you will use some of your rear delt in addition to your back muscles as well.
Also, in re to your question about using a straight or curl: from my experience, you can use both... I find a curl bar feels better on my wrists for when doing rows, but that could be just me.
Take care, Lynn M.