I've been using a very basic midi keyboard controller that I've had since before DAW's were invented (They were called sequencers back then) and the pitch bend wheel is mishbehaving so I'm considering a replacement.... and this where it gets complicated for me as there's so many options.
 
I dont play keys (I'm a bass player) so just use a keyboard to input the ocasional midi part from an external sequencer or trigger the odd sample.
 
As most daws come with a few soft synths I'll be able to use the keyboard to change synth parameters.
 
I've noticed that a few midi keyboard controllers don't actually have any midi ports so midi data must be transferred via USB...Im a  bit unsure of this as I'm not overburdened with spare usb ports and I'm also concerned (rightly or wrongly) of possible USB bandwidth issues when you consider there are a few external drives connected to the system
 
Also I'm guessing that no matter how many controllers are on the keyboard there will never be enough... so is it worth getting knobs and sliders that you might ocassionally  use
 
So to key or not to key . . . but which one to get  . . . and not spend a fortune

I wouldn't worry about USB bandwidth. Remember, MIDI used to run at 31.25 kHz (not MHz!) date rates. 5-pin DIN connectors are becoming less and less common on controllers. You could probably run your keyboard from a powered hum that also accommodates your mouse.
 
There are a bunch of decent controllers on the market. The main differentiation (other than price) is:
 
1, Number of octaves. This also determines size. More octaves are helpful if you have sample libraries with keyswitching, but it doesn't sound like you're that deep into it.
2. Minikeys vs. full-size keys. Depends on the size of your hand and available space.
3. Controls and Mackie controller compatibility. That means can control Sonar parameters from the controls, although sometimes head-scratching is required.
4. Aftertouch. To me this is very important but I'm probably in a minority. I like being able to control parameters like vibrato depth by pressing on a key once it's down.
5. Weighted vs. unweighted keys. I prefer unweighted for controlling synths, it's what I'm used to. Real piano players like weighted keys.
 

The midi for usb standard actually transfers data much faster than the original midi standard, and pretty much breaks the 16 channel limit. MIDI USB RULES.
 
http://www.usb.org/developers/devclass_docs/midi10.pdf
 
And the data transfer is still so small relative to audio etc., that you can easily push it through a USB hub without worries, as long as the driver for the device you are feeding can handle the hub.

I use a Roland A-800 Pro which was built for Cakewalk and has the ACT function built into the keyboard.
It has all the sliders and knobs that I need.
The only thing I wish was that it had more pads.
 

I just replaced my very old Roland with a new one..the old one started life with an Atari 1040 fr a bed partner that's how old it was. The A49 ($ 135 Can).  is perfect for a small space and us hackers. It has an  "expensive" feel to it to, I tried a lot and they felt like toys. It has both USB and MIDI so you are saved from USB hell...
 
http://www.gearslutz.com/board/reviews/917212-roland-49-a.html
 
 
 

I current have three controllers connected. An old Roland XP10 via the 5-pin DIN on my Quad Capture which goes to the PC, along with any audio, via the Quad Capture's USB. A Cakewalk A-Pro 800 connected directly to a USB2 port and a AKAI LP-25 mini keyboard (mainly for key switches) conneced via a powered USB2 hub. I have not encountered any issues with this setup.
 
There should not be any issues running Mouse, QWERTY keyboard, backup drives and memory sticks via a hub. I prefer a powered hub.
 

I'm like you, and only use midi for an occasional pad, synth part or to play drums.  I have a MAudio keystation 61.  Connects via usb (no drivers necessary for win 8) and performs perfectly.  It is exactly what I like in a piece of gear:  plug in single cord and never think about it again.  
 
http://www.sweetwater.com...6ayb1r4CFQNqOgodGD0AnA