If you need to shoot in tight spaces, or have a nice field of view, the 50 will hold you back severely. On a full-frame camera, a 50mm lens is "normal," i.e. captures about the same perspective as the naked eye. Swinging the camera around while you look through the viewfinder is about the same as looking around with your eye.
On the D3100, a crop-factor camera (Nikon calls it DX,) the 50 is actually a short telephoto lens, even a decent portrait lens. You won't be able to capture an interior space with it, and anything of any size you want to photograph will need to be some distance from you. No group shots on the balcony, for sure.
On the other hand, if you want to get details of something that IS far enough away, your cell phone might work better than that 50, and you'll be wishing you had the 200!
If you're only going to carry one lens, make it versatile. The 18-200. Yes, it's nearly 3 stops slower than the 50-1.4, but are you gonna be shooting in the dark? Shooting what? Even at f:1.4, if it's really dark, like night on the streets, you'll need a slow enough shutter that motion blur comes into play, so you'll be popping up that flash. The speed doesn't help you, then.