Any particular model for the dogbone or open style cases you prefer?
I am all about fanless, so holes for mounting one are superfluous for me. Nice thick acrylic like the Sunflower 1000C2 (around $10 on ebay with free US shipping) with silk-screened I/O labels or any of a number of other direct-shipped-from-China units. Don't pay more than $10-12 US - you are being gouged. There are even ones with the one plate extended to support 75 or 100mm VESA mounting for a few more $$, so you can hang it on the back of your monitor. An 18" HDMI cable, USB powered hub ( I lik the Sabrent HB-W4U3 with 5V 4A ps) to power the Pi and external drive, along with a Logitech K400 Plus kb (currently $20 at BestBuy) and you are set. Some of these cases let you mount an 'internal' 2.5" HD or SSD, if you get a double-layer case and the 'ears' on the dogbone are large enough to squeeze in the drive. You can always drill your own holes, too - it's an acrylic plate after all! WD makes drives with SS USB connectors rather than SATA - so a USB to SATA adapter or external drive case is not needed.
If you like the 'techie' look with all the guts exposed...
I prefer the dogbone or open style acrylic cases. You can adjust the 'plate' heights for whatever heatsinks (and/or fans) you prefer and there is no heat buildup as in a closed case. A second alternative is a metal case, like the Flirc or Eleduino.