Lately, I've been feeling a slump and wanting to watch more romantic dramas with leads as awesome as the ones in Cheese in the Trap who will totally keep you addicted. I've got She Was Pretty on my radar but not sure if that will cover my heartache while waiting for new episodes! 

I want something with plenty of romance, lots of interesting plot twists and something that will melt the heart.

Romantic dramas I've loved a LOT:

Kill Me Heal Me, You're Beautiful, Pinocchio, I Hear Your Voice

I tihnk it was also because there were other elements to it that were going on (like the crazy stuff in I Hear Your Voice with the psychotic guy, and the back story to Pinocchio etc). Anyone?

I just finished Ho Goo's Love and found it very addicting. Light-hearted and funny and easy to finish quickly. Based on the others dramas you've listed, I also recommend Queen In Hyun's Man, The Master's Sun, Two Weeks, and Sassy Go Go! They all have a decent amount of romance, some twists, and a little heart-melting ;) I'm so addicted to Cheese in the Trap right now too hahah
The Princess' Man - there is a ton of interesting things happening around the romance and I found it suuuuuuuper addicting  I think I finished it in like 2 days and there were 24 episodes. Lol  

The Master's Sun -- Very intriguing storyline and I thought the actors did a good job.

You Who Came From the Stars - Entertaining and I thought all the characters (even the bad ones) were entertaining. 

Kill Me, Heal Me -- There's a lot of backstory that's revealed as the drama progresses. I thought it was very well made. 

It's Okay, That's Love -- I couldn't stop watching. Everything played out perfectly as you learn more about the characters and why they act the way they do. 

Ahh, yes! Ho Goo's Love is definitely on my to watch soon list.. I also want to watch Sassy Go Go and The Master's Sun! I've heard alot about the others, so I definitely am gonna think about what I want to marathon next. :) I also need to watch You Who Came From The Stars since everyone talks about it ^^

I LOVED Kill Me Heal Me, I didn't want to part with it and let it finish haha... Shin Se Ki <3

I absolutely loved Kill Me Heal Me, I Hear Your Voice, and You Are Beautiful. And I found these enjoyable - particularly the first four :):

Secret (its Ji Sung & Hwang Jung Eum before Kill Me Heal Me) - romance with revenge plot 

Falling for Innocence - romance, comedy with a murder mystery plot

Protect the Boss (Ji Sung & Choi Kang Hee) - romance between immature CEO and down to earth secretary - cute and hilarious 

High School King of Savvy (Seo In Guk & Lee Ha Na)  - brother stands in for elder brother CEO and falls in love with office worker - has to swap between school uniform and office clothes .... its really romantic and hilarious.

Secret Garden (Hyun Bin & Ha Ji Won) - romance and fantasy (swapping bodies)

Witch's Romance (Uhm Jung Hwa & Park Seo Joon) - noona romance
"I want something with plenty of romance, lots of interesting plot twists and something that will melt the heart."

You should really try It's Okay, That's Love !
Great actors, genuine plot, lots of romance, a mixed of melo-rom-com.
u wanted some heart melting dramas here u go 
operational proposal ............. its my fav love drama n its got time travel which makes it moreinteresting
missing you ............... many romances as childhood n later on also . it will certainly give u warm feeling

i second princess man n queen in hyun man . both r good especially princess man

most of ur fav r my fav also . btw why is ur list surprisingly short for someone who is long time user
there should be a category like too much good dramas
Ahh @midori, I loooved Protect The Boss! It was the first drama I saw Ji Sung in, and he's so adorable in it! :) I also loved Secret Garden, so I can imagine the rest of your suggestions will definitely be to my taste! Witch's Romance was on my to watch list as I love Yoon Dong Ha!

It's Okay That's Love is also on my watch-list! I have not heard of Princess Man and you all have mentioned it at some point so I must check that one out! ^^

Thanks for your suggestions everyone, definitely need some cute stuff to pass the time :)
haha oh @amitspiky - because I went through periods where I wasn't watching drama for one reason or another, that's why I am trying to watch more and catch up haha. I've been a drama fan for a LONG time but I tend to watch lots of other stuff too (lots of US stuff and movies) :)
Oh my gosh, @catstreet ....I'm totally jealous that you got to experience The Princess' Man for the first time. :P

Like seriously, it's been the only full historical period drama I've watched (so far in my drama watching journey), but it was the most addictive of all dramas I've watched so far (and that includes Cheese in the Trap). 

Okay....*maybe* they're tied. lol. :P
Haha wow, well it looks like it's very popular so hopefully I will love it as much as everyone else does :D

It's always good to watch stuff for the first time! I wish I could experience some of my other fave dramas again, haha!
Ugly Alert
Marriage Not Dating
One's I've been addicted to are:
Oh My Venus
Master's Sun
Love Me If You Dare
Down With Love
Bromance
You Who Came From The Stars is definitely something not to miss.  It has the supernatural element, and the humor is really well done.

Marriage Not Dating was cute, and it is largely about the comedy and romance.

Love Me If You Dare is amazing, but its is definitely more thriller/mystery than anything else.

The Princess' Man was really good, but it is similar to Love Me If You Dare in that I would say it focusing more on revenge than romance.  Though the romance in both is definitely there.

As I have said in a lot of other topics Falling For Innocence is one of my favorites, that and Cruel City.

Light Hearted - Marriage Not Dating, and mostly You Who Came From The Stars.

Serious tones throughout, romance, with random comedy - Falling For Innocence.

Romantic Thrillers - Cruel City and Love Me If You Dare.

Romantic Sageuk Revenge - Princess' Man.