Now... that's a broad search!
I feel you on Boys over flowers... it was so bad!
From your "plan to watch list", you really can't miss:
Another Miss Oh - romance. check. plot. check. best side couple ever. check. This is really good, great actors. The "seeing the future part" is actually quite small.
Coffee Prince - the classic drama you must watch. It has some really good romance.
Witch's Romance - cute and funny drama. That first scene is a must watch at least.
Other drama that could fit your search:
Bring It On, Ghost - nice supernatural drama, quite good romance... with the worst kisses ever. (must have something to do with the lead actress being underaged at the time I guess)
Drinking Solo - great drama with some nice romance, quite funny too. And a great cast and a great set of characters.
Lucky Romance - I don't usually recommend this one as I didn't really like it. But it's comedy and romance. People seem to have really enjoyed it.
Oh My Ghostess - supernatural/thriller and romance. the lead actress is really really good!
Queen In Hyun's Man - Part of the drama is historical (yay! for time travel), but it's not most of the drama, so it should still be ok for you. Sweet couple and great chemistry. It has a lot of really cute scenes and lovely moments (totally falls in the guilty pleasure category)
Since you mentioned noona romance:
What's Up Fox? - It can be a bit dated (video rental anyone?) but it's still totally watchable and overall really good, quite funny too. Although a lot of people have found the side stories were taking a lot of screen time, I actually liked them.
Secret Love Affair - I have the feeling you are looking for something light hearted. This is not. Not at all. But it's really really good. The actors are brilliant. Besides the romance, there's a school politics/finance plot going on.