The point is, use what works for you. And don't let anybody tell you different. If the kit lens is doing what you require by all means go for it. If you still want a upgrade I would reccommend this EF 28-135mm f/3.5-5.6 IS USM <--- click on this.
It is a very good all around lens and at it's price point a real jewel.
And the very best buy in a Canon L lens is EF 24-105mm f/4L IS USM <--- click on this
It can be had in what is called a "white box" version for about $700 bucks. It is a full blown pro "L" quality lens. Plus there are always good used ones, sometimes in the $500+ range.
However, if you are good with what you have, just use it and take lots of pictures. 
