I'm a simple short-commute cyclist. To me, being able to just hop on the bike and go is key to what makes biking tolerable and fun. My commute is six miles each way. I have a bike with an 8 speed IGH (Alfine), but my backup bike is a 1971 Raleigh Sports, and I can do it OK with that bike too. (An IGH seems the way to go to me for all-weather frequent but somewhat short and traffic-filled trips) I wear normal work clothes, but my work allows somewhat casual dress, especially in the summer when I can wear shorts and sandals.

I usually wear a Champion Double Dry shirt as an undershirt. I bring (or have at the office) an extra t-shirt just in case, but I rarely use it. I use a small pannier for my computer and a few other small items. In the winter, I may have a merino wool layer underneath that must be removed after I get to the office, but this is a rare occurrence here in DC. On the handful of truly sweltering days, I may bring a change of clothes. I have some quick-dying compression boxers, but don't always wear them. I try to carry a hankerchief with me on all commutes in all seasons. It's proven useful in many ways, but if nothing else I can wipe myself off if I'm perspiring or cold-induced nose running before I even go into the building, even if I am going to do more clean up inside.

One of the unexpected side benefits for me of being more upright and not being geared up is that motorists give me a wider berth on average. Also, people seem to treat you a little nicer overall.

I have added a chainguard to my bike. I notice most (or many) posters on this forum have the essential fenders, but few have chainguards. I think the chainguard is key to the whole "ready to ride anytime" thing. Back when I didn't have a chainguard, I had a couple of those velcro straps for pants, and one of them was always strapped on my rack, so I could always get on the bike, but this just isn't the same experience, and doesn't work as well if you have pants with lots of fabric down by the ankle, as a chainguard.

I have been reconverted to platform pedals. Again this fits in very nicely with the whole "just get on anytime and go"/less gear thing. There's a great freedom of not being tied to the gear. I have no foot slippage issues. If you are wearing a hard sole dress shoe (especially in the rain), or a new shoe where the bottom hasn't broken in yet, you could have some slippage. You can get BMX pedals like the Tioga Surefoot with pegs that make the pedal very secure for all shoes. You can bike in any sandals/shoes/boots.

Classic swept back North Roads-type handlebar is a good way to go for the bike used for shorter commuting. Very comfortable and natural for the upright riding. I switched my bar (which I think originally was the same as a Soma Noah's Arc bar, but later I changed it to a 52 cm Soma Sparrow bar which wasn't quite right) to the 56 cm heat-treated aluminum Nitto North Roads bar. This Nitto North Roads is actually shaped like the Albatross bar with complete sweep back, rather than the angle on the traditional NR or the Nitto 50 cm NR bar. This bar allows me multiple hand positions because the curveback portion is large enough and out plenty wide enough to provide a great place to put hands. I put leather handlebar covers on that portion of the bar, and this works great for me. You really don't need multiple hand positions for short commutes, but I still do like to shift around and get out of the wind a tiny bit sometimes. Also, this is my only bike for longer trips as well.

I like having a dyno light, at least for the front. It's very nice not to worry about recharging. I do have a supplemental battery light that I leave the mount for on the handlebar, with two copies of the light (one at home and one at work), but I only use it if I think about doing long rides in very dark, and even then if I don't have the extra light, it's no big deal. I would like a dyno light in the back too, but I don't have that, and the batteries last a long time for the blinky. My back light does go on by itself if the bike has been moving and it is dark (and off in light or stopped long enough), so that is nice not to have to fuss with as well.

I also always have cargo netting (whatever you call it) on my rear rack. This is great for always being able to jump on your bike for utility trips, or picking up food at lunch time, etc. I've done a similar thing with bungee cords in the past, but the netting is much better.

I don't carry full sets of tools and tubes when I commute because I basically follow the Metro (subway) line most of the way, and am never far from a station (or work/home). However, my bike always has a simple single piece Park multi-tool strapped to the frame of my bike. Nice not to have to fiddle about with that. I leave my bike parked outside all the time when I travel to work or elsewhere, and no one has ever stolen the tool, but it would be no big loss anyway. I've haven't had a quick flat in many years of commuting. I think fatter tires are much less likely to get flats, but it obviously depends on your location, but for me it is the same in my last four cities in three different time zones on three different bikes.

That Raleigh Superbe looks just about perfect for a short commuter mass-produced bike once the rack is added. Although, I think you could argue that the price is getting close enough to where you could spend some more and get a custom one, like an ANT or whatever is appropriate for your area. I think my next bike may be a custom bike from Velo Orange, but I am many years from saving up enough money for it. Most of these type of bikes don't have disc brakes like the Superbe though. I have disc breaks now, and they do stop well in the rain, but would be willing to do without them. There are cheaper bikes sold in the US than the Raleigh Superbe that are somewhat similar, but I can't think of one that has disc brakes, Alfine, swept-back handlebars, chainguard, etc. You'd have better luck in Europe. I don't know why bikes like the Breezer Uptown (which also doesn't have disc brakes) don't do a north roads-type handlebar, instead of flat; it would be a perfect fit. I remember looking into bikes with similar key features about a year ago and coming across names like Breezer Uptown 8, Bianchi Milano, Masi Soulville, Jamis Commuter 3, Biria EB Superlight 8, Electra Townie 8 Commuter, Specialized GlobeCity6, Novara Fusion, Redline R530, etc. All are a little cheaper than the Superbe, but outside the rack, are generally lacking something the Superbe has. They aren't that cheap either; New Alfine and Nexus 8 bikes aren't going to be that cheap. I think many people who don't live in an area with serious hills can get quality bikes for less for their short commute by dropping the disk breaks requirement and getting a cheaper IGH. There is a blog called "Bikes for the Rest of Us" that covers these types of bikes in the US: http://bikesfortherestofus.blogspot.com/. If you could get a Pashley or Velorbis or something from Europe, you would be good to go as well.

When in doubt, you can always get ideas from http://www.copenhagencyclechic.com/
The Dutch and Danes are way ahead of us.