There's another good one.
It's called the "mechanical engineer's pocket reference" or something like that. It's by Shigley. I've never seen a pocket that could actually hold it, it's about 10 lbs.
From my experience, any of them are fine 9 times out of 10. It's that 1 time out of 10 that you want something really obscure that you end up with all of them open on your desk.
It's fun (and sometimes useful) to find a really old one. I've got a Marks from 1919. It has entire sections devoted to things like steam power, and making and preserving ice (big business in 1919).
Also (and I'm going to be a little anal here), look at your "machinists handbook" that you mentioned and I think you'll find it's called "Machinerys Handbook". I don't know why it bugs me, but 90% of everyone who has one calls it the wrong thing. That's the book I always start with, then go to Marks or Kents, then if it's really obscure stuff get out Shigley's handbook (or I used to back when I had one).
Have Fun,
-Dan M