I'm driving down to North Wales next week, and i remember reading an article once about some great roads for Aston's around Snowdonia but don't have the details. Thought there may be some locals who could recommend. I'm also aware there are some good tunnels on the A55.
I took 13 cars inc fellow PH'ers on a 2 day jaunt in April that saw us touch the tip of the Lleyn Peninsula - happy to PM you my route, and as a local!