This is really what it comes down to. My cyclocross commuter is a bike with drop bars, but the bars are much closer to the saddle height than my road bike. Since the handlebars are higher on my commuter, riding in the drops isn't uncomfortable at all - but I still do spend most of the time in the hoods. Riding in the drops on my road bike is more aerodynamic than my commuter since I'm lower, but I do have to focus on my posture more.

I love handlebars with drops because there are so many choices for hand positions, and with the cyclocross brake levers on the tops you can brake from anywhere. If you don't like them low you can always just get them higher relative to the saddle height by picking the right frame - the same goes with any kinds of handlebars

5km is just over 3miles. Nothing wrong with going with a more upright position. The difference in commute time will be pretty small over 3 miles. You may keep you fitness jaunts shorter as you will work harder to go the same speed as drop bars / narrow tires. I personally commute on drop bars with spd pedals but have a longer distance to go.

Just keep riding.

5k = 3.6 miles. A fellow could do that on a big wheel.

I'd have trouble fitting on one of those...
http://t2.gstatic.com/images?q=tbn:A...i6gKVPKW_Xcd7w

The seat goes back! :D

To make an actual contribution to this thread and respond to the OP's question: I'm a drop-bar guy, for similar reasons listed by others: several different hand positions give you multiple positions for many types of situations. (I even had a flat-bar mountain bike converted to use drop bars.) All three of my bikes have the bar tops just below the seat height, so with my hands on the tops, I can still sit fairly upright (obviously not sitting straight up though!) The hoods are the most natural position for me, and the drops let me get a little more aero on windy days.

I've done a 40k round trip a couple of times with a very upright/north roads position. I don't mind.

If it works for you, please, please don't let someone tell you it doesn't.

Cool. That stretch just north of Navy Pier is the worst on a windy day. I myself ride from Wilson/Pulaski to Wilson/Trail and then Trail/Jackson.