For cityscape, I usually prefer a wider to standard focal length lens. And that is what your kit lens' focal length falls into. And if you would like to pick up a decent lens in that range, the Sigma 18-50mm f2.8 EX DC Macro HSM or the Tamron AF17-50mm F/2.8 Di-II LD Aspherical are pretty good choice. (esp for lower cost)
If you prefer a even wider view, the Sigma 10-20mm is great choice as mentioned by Overread. (Tokina 11-16mm is also a great choice)
As for portrait type photography, I prefer a telephoto lens range around 70 to 100mm if space is not limited (i.e. outdoor). I use my 85mm lens a lot for that. Or the standard prime lens with 50mm focal length is a good choice especially for indoor limited space (On a cropped sensor body such as your camera, 50mm may still be too long for tight space indoor environment.)
As for the macro/close-up, there are 1:1 ratio macro lens that you can also use it for portrait. You will find some prime lens in 60mm, 70mm, 90mm, 100mm, 105mm, 150mm or 180mm ... Those are dedicated macro lens that allow you to have 1:1 magnification. The Sigma 18-50mm lens I mentioned above do have a macro function (close up), however it is not really a true macro lens, but it allow you to have close up shots, (The Tamron can also focus decently close as well)
In general, the higher price lens offers better optical quality. If you find that your photography is limited by your current lens, you may want to upgrade it to a better one.
For me, I will usually look for a faster lens in which the maximum aperture is larger (lower the F number such as F/2.8 or lower). Faster lens usually (not always true) optically better and works better in low light photography. But it usually comes with a higher price tag.
Good luck
