The 18-70mm is probably the best choice with the 18-55 kit lens being second. Be warned, neither is terribly fast, but both are sharp (especially stopped down a little). You can't beat them for the price. You won't get a fast zoom unless you're willing to part with a good chunk of change. Fast, inexpensive zooms do not exist..if a zoom is fast, it will not be cheap.

The Tamron 28-75mm f/2.8 XR Di is a popular choice for around $400.00 (especially since Nikon's 28-70mm f/2.8 ED-IF AF-S Zoom sells for over $1,400 discounted at most vendors).

It won't have the focal range of some lenses, it doesn't have Nikon's AF-S (silent wave motor) focus system, and it's going to be larger and heavier than the kit lenses, but it's sharper and brighter (it can maintain an f/2.8 aperture throughout it's focal range) and most users report good AF speed from it, too.

But, you may or may not want something starting out wider. Also, even though you can get by with an f/2.8 lens indoors without a flash in some lgihting, the 50mm f/1.7 is more than twice as bright. So, if budget permits, I'd pick one up for low light use without a flash (even if you need to get it used).

Speaking of used, I wouldn't ignore that option. You can often find some bargains in used lenses at vendors like http://www.keh.com , http://www.bhphotovideo.com and http://www.adorama.com

Make sure to take a look at lenses you're interested in, so you'll have a better idea of how size, weight and ergonomics compare. Any choice is a compromise.