At your weight, I'd stay with the same size tire. This will allow you to have a reasonable tire pressure to prevent a pinch flat and have low rolling resistance. If you can't find another 700x30c tire, then go with 700x28c in front and 700x32c in the rear.
__________________
What, Me Worry? - Alfred E. Neuman
I'd like to think i have as much money as brains.
I see the light at the end of the tunnel, but the tunnel keeps getting longer - me