^^Chicks dig melodramatic movies
The melodrama part is just so perfect in Korean movies.
I will add to the list with a link to post in my blog:
*t.webofgoo.com/2008/05/24/must-watch-korean-movies/
*t.webofgoo.com/2008/09/14/must-watch-korean-movies-ii/
Here is the list from the above blog posts which you can safely tell your sis to watch (I am excluding gory and explicit movies here, leaving only melodrama and romcoms):
1. My Sassy Girl
2. The Classic (you have already watched it)
3. Sad Movie
4. A Moment to Remember
5. Marathon
6. ...ing
7. Lover's Concerto
8. Once in a Summer (you sis will really love this movie)
9. Lump of Sugar
10. Windstruck (My Sassy Girl's spiritual successor...lol. But not as good)
11. The Beast and The Beauty
12. My Little Bride (This is just hilarious, every moment is at par with My Sassy Girl)
13. A Millionaire's First Love
14. Welcome to Dongmakgol (anti war)
15. Love Phobia
16. Please Teach Me English
17. The Host
Some recent ones I watched:
1. My Girl and I (end is really well done)
2. Shiri (anti war movie)
3. 200 Pounds Beauty (romantic and good music, thats it)
4. Joint Security Area (anti war movie)
PS: Get you sis some kleenex before watching them ;p