Recommend me something cheerful

I recommend Haeundae Lovers.  Although it has received only a 7.0 rating to date, it's an easy and fun drama to watch ... as long as you are not looking for "substance," and you are not. The pace is fast and the acting is VG.  If nothing else, watch this for Kim Kang Woo and the "uncles."

If you're in the mood for trying out a Chinese drama, a really cute and light-hearted one is Boss & Me. 

Also, it's a classic K-drama and I saw that you haven't watched it yet, so I'd also recommend Coffee Prince. It's a gender-bender with some really cute and light-hearted, cheerful moments. Whenever I hear the OST it makes me happy. :) 

The Thailand version of Full House is super-duper light-hearted and cute.