For romance, Cape Sounion (Temple of Poseidon) Day-Trip delivers.
Watching the sun drop into the Aegean behind the gleaming marble columns of Poseidon's temple is a deservedly famous, deeply romantic payoff, and the coastal drive down the Riviera is lovely. The catch: it's a 70km round of 1.5–2 hours each way, sunset means a packed temple and a late return, and by day the ruin alone is a quick look that doesn't justify the trek.