Well it depends on the aperture of the lens as well. Say a lens that's designated as 50mm f2.8; f2.8 is the aperture which how big the lens can open, the smaller the number, the bigger opening (it's weird concept I know). If you take that lens, shoot it at f2.8 of a subject, you'll have a somewhat of a blurred image in the background. If you take say a 200mm lens with the same aperture, the blur will be even more visible.
But if you 'stop down' the lens where you close the aperture to say f8, you'll have an image that you can see the background more. It really depends what you're shooting. Sometimes you'll want to stop down to take a picture of a subject with no background blur. Generally f2.8 and larger (up to f1.2 lens) is expensive as the construction of the glass is bigger to allow more light but can take very sharp images. Not to say other lens can't but it's also nice feature in low-light setting.
I'd definitely get a zoom lens that can offer between 35mm~200mm. It'll be versatile for wide angle shots to up close/macro or the blurred image shots.