I just want to provide an update and that I skipped Harlech. All accomodations we called were full for the night that we wanted to spend in Harlech. As a result, we just stayed in Porthmadog and spent 1.5 hours in Harlech in the morning. Of course the castle was closed, but oh well, there's always next time. I went to Caernarfon, Beaumaris, and Conwy instead.

Thanks again for the help boys!