Alternatives to Canon's 15-85mm lens?

In a recent forum post, most of you suggested that I purchase a Canon 15-85mm for an upcoming trip to the U.S. Southwest.  But I couldn't afford it.  That is until a little while ago when Santa presented me with a Gift Cert. to B&H enabling me to purchase one.  But before doing so, I'd like to know if there are any other lenses out there that I should at least consider before making the order official?  I currently have a Canon 70-200 f4 IS lens and a Sigma 17-70mm lens (which will be sold when the 15-85---or another similar lens--is purchased). The tele isn't going anywhere.

So, just before placing my order for the 15-85mm, are there any other similarly good lenses (for about the same $$$) that I should look at?

Thanks