My sixth sense tells me I'm not going to make many friends with this article, but I'm just going to say it: if you carry a bag over or across one shoulder, it's a purse. That means all those messenger bags you fellows are carrying around are man purses. I don't care how big it is: it's still a murse. And I've already earned the ire of one coworker by calling it that (I believe his exact words were: "I'll murse you"), so if you want to bombard my comment section with disapproving statements, I fully understand.
But before you get all aggro on me, allow me to state for the record that the man purse gets a bad rap. What with all the gadgets we're carting around on a daily basis, it's only fair that men have the same spacious options that women do. The murse is highly functional, and many options available right now are very stylish. So yes, DO carry one.
Also, DO consider investing a fair chunk of change in a nice, durable bag. One that appeals to your eye as well as to your sense of practicality is the best bet, as most likely, this is going to be the only bag you're carrying around day after day. You should want to look at it. Hey, I'll say right now that I'm jealous of the "one bag for everything" phenomenon you gentlemen get to indulge in. Do you know what a pain in the neck it is to switch purses to match an outfit day in and day out? A giant one.
For men, one of my personal favorite bags is the Chrome Citizen Fowl Mood bag. Or if you prefer something slightly less in-your-face but still with a bit of unique style, check out the Angel of Death version. True, both of these options steer away from the plain templates I see most guys cruising around with, but displaying a bit of individuality through your bag shows confidence--always a good thing.
If you find yourself in and out of airports with some amount of frequency, DON'T pass up a bag with an integrated, padded pocket for your laptop--one with easy in and out access--such as the Timbuktu Command Oxford Nylon Fabric bag. Having a separate area for your computer will keep it from getting dinged by other items rattling around, and the convenient location will make going through security a slightly less painful process.
As a bit of an aside, if you come across an otherwise-amazing bag that lacks that laptop pocket, DO pick up a separate protector, such as the hard-sided Speck SeeThru shell or this less-weighty, soft neoprene pouch. (You can even leave something like the SeeThru on your computer as it goes through the X-ray).
Also, DON'T be afraid of the satchel or something a wee bit smaller if you don't need to carry a laptop or a lot of other stuff around with you. There's no need to have a giant bag slapping against your side if it's mostly empty. This Pier Traveler Men's Bag is the perfect size for a Kindle, a smartphone, a wallet, and some keys--what more do you need, really?
However, DO recognize the fine line between a man's bag and a handbag. I don't care if you stripped the leather directly off of Indiana Jones, that bag on the right is a purse, minus the man.
Finally, if it wasn't already obvious, DON'T buy a pink camo bag. Not that I mind the color pink being "liberate[d]...from the female gender," but frankly, that bag is just ugly--for a man or a woman.