Canon's Image Stabilized midrange zoom is a favourite "walkaround" and vacation lens.

Many people have trouble choosing between this lens and the 24-70mm f/2.8 L. There's no simple answer; they're both great lenses. The advantages of this lens compared to the 24-70 are that it's smaller and lighter, it has a longer range, and it has Image Stabilization. On the other hand it's a full stop slower, may be a little less sharp, and exhibits some barrel and pincushion distortion at the extreme wide end of its range on full frame cameras. The 24-70 is probably more at home in the studio, and this is the one for when you're out and about.

Why not hire both, and compare them for yourself?