Advice Pros and Cons of Cardiff, Conwy, and Penzance

Greetings all. I’ve been working on the first travel leg for this summer and am looking for ongoing advice on choosing between Cardiff, Conwy, and Penzance. Each seems to have its unique charm, but I’m curious about the pros and cons of each from those who’ve visited. Cardiff seems vibrant with its castle and museums, Conwy offers that medieval vibe with its walls and castle, and Penzance has that coastal charm with access to places like St. Michael’s Mount. For those who’ve been, which would you recommend for a mix of history, culture, and relaxation? Any hidden gems or drawbacks I should know about?