You may have heard mention on these boards of the Kelly lens, which is a DIS nickname for the Sigma 18-125 digital lens.
However, Sigma also makes a 28-200 lens for non-digital cameras. The 28-200 has the same field of view on a Rebel G as the 18-125 has on a digital camera. I have a Rebel G and a Sigma 28-200 that I have been using since 1999, and have gotten some fantastic pics with that setup (although I recently bought a Digital Rebel and a Kelly lens, so I'm trying to sell off my Rebel G and the lenses I had for it).
The Sigma 28-200 is a terrific walkaround lens with a great range of zoom for places like WDW, and is not terribly expensive. I highly recommend it as an affordable lens for a Rebel G.