Oooh, I'm late late late, but thank you for this post! Harlech looks properly medieval and I can totally understand that it made an impression. I've been to Wales once, for the Eisteddfod in Llangollen but didn't see any castles unfortunately, just lots of Welsh countryside which was beautiful.

I would very much like to visit them again, but I am almost reluctant to do so, in case I don't feel the same way, if that makes any sense at all!

That makes perfect sense, as I have been a bit disappointed visiting places again (usually after a couple of years, being older) and the magic was just gone. Or very different.

I loved the Georgian architecture in Dublin so I'm sure Bath would be right up my alley.

Nottingham, and the castle there, and the forest

Hey, Nottingham I can reccommend wholeheartedly, I spent two semesters at the university there (years ago, but still). The castle has been burned down and is more of a mansion now (castle gate has been reconstructed, so you get an impression what it used to look like). It houses an art museum now which I really liked. You also get a fantastic view from there because it's high on a cliff full of caves (which I didn't get to visit then, a fact I still regret).