Question Help with a 6-Day Seoul Itinerary

Hello everyone! We're a couple in our late 30s, and we're heading to Seoul for the first time in just under 2 weeks! It’s a last-minute trip, so we're looking for some help. We love exploring local food spots, cultural experiences, and maybe a bit of nightlife too. Any tips on must-see places or hidden gems would be awesome! Also, how do we get around? Is the subway user-friendly? Thanks in advance for your suggestions!