Yes, that lens should be enough for general landscape (not the ultra wide kind, which is a specialty lens for landscapes). Should be good enough for portrait as well, but indoor it will suffer unless you set the ISO levels to much higher levels (which will invite much noise levels). Landscape-wise, not the widest but sufficient if your landscapes are not broad horizons (should be fine for some cityscapes, etc).
Since you have that lens already, my advice like Smiles88 mentioned would be either AF-S DX 35mm f/1.8 or AF-D 50mm f/1.8 to couple with your kit lens. These two are very affordable fixed focal/angle that is great for indoor/low light shoots (due to the large f/1.8 aperture - no need to boost up the ISO). Good for indoor portraits.
Thanks to all the bros for all the expert advice. I will explore my kit lens first then, will get the Portrait next then before my trip.
