All right... I am loving rich boy poor girl dramas... One of my favorites is Lie to Me or even Secret Garden...

any other good dramas that I should watch? 

I'm not huge on chaebols, but one drama I do like quite a bit is shopping king louie. I also suggest mask, my name is kim sam soon, protect the boss, & fated to love you. I dropped FTLY but it is a very popular drama regardless, as is mask (which I had to put on hold). cheese in the trap is an interesting drama, even tho I don't particularly like the end & stopped enjoying it around ep 12. unless I remember incorrectly, I think me too, flower! falls under the chaebol drama category. the leads are cute together but the drama itself is nothing to rave about, yet I still enjoyed marathoning it. 

others would be...
boys over flowers (I will never rewatch this but it is a popular pick)
heirs (by secret garden writer kim eun sook. I felt super bored with this)
falling for innocence (felt it was a lukewarm, tropey melo but watchable, kind of addicting)
beautiful gong shim (good start but the focus shift from fmc to mmc greatly disappointed me & the ending fell flat IMO)
goong (I watched this for the young YEH, but I wouldn't sit through it again lol...)
flower boy ramyun shop (no opinion/dropped after ep 2)
cheongdamdong alice (got draggy; dropped)

^^^ I don't personally rec what I didn't bold but you never know what someone else's preferences are. master's sun is another popular one that lots of people seem to enjoy, but I have yet to watch it.

I hope you find something to enjoy (:
The above is a pretty good list. I'd like to add:

Kill Me Heal Me
Jekyll Hyde and Me
W

of those I enjoyed 1 and 3 the most although Jekyll was still decent.
Scent of a Woman - I love this one

Boss & Me (chinese) - Super cute in the beginning kinda drags towards the end

My Girl - My all time favorite

Cinderella and the Four Knights - the name itself gives away the plot

The Heirs - everyone besides the heroine is a chebol

Moon River (taiwanese) - a bit like boys over flowers

Bride of the Century - Spoiler(the heroine pretends to be a chebol)

High Society (the second leads are what you are looking for) 

Last Scandal (Hero is a superstar she works as his housekeeper -very funny)

Sunny Happiness (taiwanese) - cute in parts
 
The Master's Sun - supernatural elements but awesome drama

Loving, Never Forgetting (chinese) - didnt enjoy this one very much

Office Girls (taiwanese) - Hero pretends to be poor

My Daughter Seo Young - 50 episodes

Marriage, Not Dating - (hero is rich but not chebol rich)

Coffee Prince - An all time classic
Agree with all the dramas already listed! A couple others that I notice missing:

Noble, My Love
Lucky Romance (male lead is company CEO and rich, but family not rich)
May Queen
Can You Hear My Heart?
Glory Jane (second lead)
Heart to Heart
Passionate Love
New Tales of Gisaeng
Heard it Through the Grapevine
Also non-Korean ones:
Fall in Love with Me (rich, but family not rich)
Bromance
Love Me If You Dare (rich, but I'm not sure about family)
Demon Girl (both male characters are well-off)
Rich Man, Poor Woman
Yes! Mr. Fashion
Prince of Wolf
A Round Trip to Love
A Different Kind of Pretty Man
Waking Love Up
Birth of a Beauty,
Coffee Prince
Fated to Love You
Kill Me, Heal Me
King of Baking, Kim Tak Goo
The Master's Sun
W
Secret garden and 1% something