Unless you love the shallow DOF of F1.4, F1.8 lenses are sharper.
I have the 35mm F1.8 DX and 50mm F1.8D, both are excellent lenses, as long as you want to shoot at wider aperture or in low light. In bright light I prefer the Kit 18-55 as that gives me zoom flexibility. For most of day light scenes I shoot at higher F stops F8 to F11, so the kit lens is perfect.
For indoor I use the 35mm extensively. 50mm on a DX sensor is a bit long, and I would prefer an 85mm F1.8G to 50mm F1.8G. For street shots in good light it is the kit lens. For getting the DOF you will any way shoot at higher F stops. If you want to isolate your subject, then F1.8 is needed.