Are you looking for an instant solution or one that you can shape over a few seasons/years ?
I like the idea of rooms/areas within a garden design it can look pretty cool when done right, soft and natural like its always been there - a secret garden. As opposed to, or lets put a vile woodern fence up with a doorway in the middle.
haha.... heres a canny rubbish sketch of what I mean. Whatever you do, a strong structure of some sort with have to be built/placed. No plant grows 6ft overnight ?
Plants to consider - climbing roses, very romantic !!