Going to the Movies in Korea is a great option for a few hours of English entertainment.
Unlike some non-English countries, Korea does not release English movies with re-recorded Korean voices (with the original English actor's voice being replaced by someone speaking Korean), but employs the use of Korean subtitles. This means that going to the movies for a night of cinematic entertainment is still a possibility for a foreigner in Korea.
A movie ticket will run around 8,000 Won ($8) per person and are bought at ticket counters or ticket machines which, unfortunately are in Korean only. Cinema's in Korea are the same as wherever you come from, expect for the subtitles on English movies. Korean domestic cinema has also exploded in recent years and some Korean movies are very famous in the Asia and the West. Korean movies do not have English subtitles, so unless you're in the mood for an two hours of nonsensical blabber, don't watch them!
Postings for films and new releases are shows outside the Cinema's or at ticket booths, but the titles are written in Korean (and sometimes changed), so you'll have to rely on you or one of your buddies recognizing a poster or actor to know what's showing! Another reason why should seriously consider learning to read Korean Script.
Two of the biggest Movie Theatre companies in Korea are CGV Films and Megabox. But there are many others so if you live in a big city, you've got a lot to choose from.