Try some leather work boots if you can't find motorcycle boots that are acceptable for you. Steel-toed boots from Wal-Mart are reasonably comfortable and provide as much protection as lightweight motorcycle boots. The only real problem is that they aren't waterproof. Assuming you don't intend to ride in the rain to work, that's not a big issue. BTW, for those who say "but steel toed boots, what if they get hit by enough weight to crush the steel toe?!" Well, given that these things are supposed to stand up to having a 200 pound weight dropped on them, if they got hit hard enough to crush the steel toe, your toes would be jellied anyhow with or without the steel toe. Mythbusters already busted the "steel toe boots are dangerous" myth, and my personal experience bears them out. Yeah, I used to work in the oilfield in a blue collar job and got to see'em in action. And your point is?
Personally, I carry my laptop and a pair of shoes in my topbox and change into my work shoes at the office. But that's because I'm missing a chunk out of my left foot from a motorcycle accident and don't feel like missing another chunk (indeed, probably going to have to go back for some more reconstructive surgery because the margin between scar tissue and skin has gotten iffy with age, I'm not looking forward to that). I have a hard time finding shoes comfortable to walk in, forget about walking any significant distance in motorcycle boots. BTW, the accident in question ended up with the hot exhaust header of my motorcycle resting on my foot for several minutes, and while it did not burn through the leather of the boot, the boot did conduct enough heat to kill a quarter inch deep of flesh on my foot. If I'd been wearing sneakers, the foot probably would have been damaged to the point where there was significant loss of function as the exhaust header burned straight into it. As is, the loss of function is minor -- one minor tendon not used in walking, and loss of some padding that normal feet have (thus the difficulty finding comfortable shoes) -- and I am extremely glad I was wearing boots rather than sneakers that day.