I used to get the .. c3.xlarge (l8 cores, 10GB RAM?... the "budget" CPU server).. I guess maybe I shouldn't say this if it's ever profitable again, but you could always get those @ spot price for .07c in US East (I had 100 running on multiple occasions).
At .07 how long did you typically retain the server for? Just 1 hour or multiple hours? How do you setup the storage so you don't lose the data when the spot ends?
Usually until I terminated them... uh, there was like one place in East where you didn't want to drop your .072c servers.... so I'd specifically select like the 'd' or 'c' subnet or w/e. I never tried to run any during afternoon-evening hours in US, it was mostly around 2am-10am, so it's possible that there's more competition later, I'm not sure
Anyway, I did it for as cheap as possible. Didn't have any extra storage besides the 8GB.
I used a script to get them running, the most time consuming element was waiting for the spot instances to be filled and then manually putting the IP addresses into putty (couldnt figure a way past that, had to input the last 2 #'s and rarely a 208 instead of a 209 as 2nd)... once I actually got on the server, it was essentially automated. for minerd, with ubuntu 13.10, you only have to grab a few things + minerd itself. protoshares takes a bit longer since you have to get libboost
(and I got a block here, with about 50hash/min total)