I totally agree with Teslinhiker's choice of footgear - low cuts are much preferable to high top leather shoes. Their lighter weight will significantly increase the distance you can hike, as well as your comfort. I would recommend after market insoles, like Superfeet or Spenco (my preference), especially on concrete surfaces.
I don't know as high tops seem to give me more support. I'd use a hiking boot rather than a backpacking boot. And in the PNW at least 3 seasons of the year the high tops are going to probably keep your feet drier. Even if you are lucky to have a dry day, which can be far and few between around here, with a major earthquake there undoubtedly will be broken water mains (and probably worse) with runoff to navigate through and around. Fall through spring I'd probably include a pair of gaiters as well.
High tops
do seem to offer more support (which is very often at debate) The problem with high top boots (whether you classify them as hiking or backpacking boots, it doesn't matter) is the weight of them. It has been proven by numerous studies that the heavier weight of the boot (which the OP has stated he wears heavy boots) makes a huge difference when you count the number of average steps per mile a person makes. The average is around 2000 steps on flat easy ground. So taking that number and multiplying it by 3 lbs for an average heavy boot is 2000 x 3= 6000 lbs of weight lifted by your legs and feet. Compare this to hiking shoes that only weigh 1.4 lbs: 2000 steps x 1.4 = 2800 lbs.
In one mile that is 1/3 less the weight and may not seem impressive, however in the course of 20 miles, the numbers are even more dramatic: 2000 steps x 20 miles x 3 lbs = 120,000 lbs compared to 2000 steps x 20 miles x 1.4 lbs = 56000 lbs of weight lifted. For any person who is even slightly out of walking/physical shape and carrying a 20 lb+ GHB, these are big differences which could be the deciding factor in you getting home before your legs and feet call it a day, especially on concrete.
If your trek home stretches into an overnight one and you stop and sleep somewhere, I can guarantee the next morning, your feet and legs are going to be hurting and you will have a rough few hours until you make it home.
As for the broken water mains flooding the street, I don't think there are very many (if any) mains
big enough that would cause enough flooding to completely obiberate a street in deep enough water that I would be worried about. Also these types of breaks are very localized, meaning if you see the water flowing due a mains break in one block and flooding the street in a few inches of water, chances are that the next block over, there would be no flooding as all the water pressure is being released in the area of the break.
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