I have MacBook Pro, late 2010.
For a while I was using OS X 10.6 and sleep logic was next:
1. after closing lid macbook go to sleep (with momentary wake up on lid open)
2. after day or so of sleeping macbook changes it state to hiberante (ram2diskc I suppose). wake up should be performed with power button and it will take some time (like several minutes or so)
Recently I've upgraded my macbook with 8gb ram and ssd + OS X Mavericks. After closing lid macbook will go to sleep, but in my case it was "sleeping" for 3 days without hibernation (and about ~40% of battery was used). On ohter hand, Mavericks has option resume apps state after shutdown and it works almost nice except I would really prefer to have hibernate instead (e.g. I need state of my terminal with open programs/running commands inside it, some background services running, etc).
Best Answer
To see what the current sleep mode is (in Terminal):
To change the sleep mode to hibernate:
To set back to the default:
More info: tutsplus - how to hibernate a mac