There are so many options available now which is part of the problem. However personally my walk around lens is the Sigma 17-70mm which I also had when I was a Konica Minolta user and was so happy with the results I got one as soon as I switched.
I also have the Sigma 10-20mm but would not class this range (be if Sigma, Canon, Tokina) as a walk around is it is too wide with not enough range. I would suggest having this on your shopping list but would agree something starting at 17-18mm is the place to look. The kit lens is probably a little weak so if you are spending hard earned money on a new piece of glass then go for something of higher quality.