Originally posted by normhead The 18-135 is more of a walk around lens.
I agree. You probably wouldn't notice the slight difference between 16 and 18 on the wide end, but you might appreciate the difference between 55 and 135 on the other end, especially as a walking-around WR lens. I wish I had an 18-135mm, that is a very versatile range, and the new most recent version of that lens is also rather compact.
I recommend considering renting some lenses in a variety of ranges, I have tried borrowedlenses.com for Pentax mounts and have been really pleased with teh experience. It hasn't made me NOT want to buy the lenses I rented, but it has allowed me to see whether they met my needs. FWIW, I rented a 21mm, and the 10-17mm fisheye, both fantastic lenses.