Landscape, macro, portraits.... Seems that u haven't really made ur mind up on what things to shoot... yet.
My advice is to stick to ur 18-55, get the 55-200 on promotion (think its going for like... $199?) improve ur skills along since these 2 lenses can fulfill everything from macro, wides, to teles. And after shooting and meditation on what u truly like and found what u're chasing after, den lean towards specialisation.
And oh yes, after u specialise, dun be in a hurry to sell off ur 2 basic lenses since u'll probably need to relearn other area aspects of photography from time to time.