My work Macbook Pro has constant problems with suspend. Sometimes it doesn't get the external display up again and sometimes it just takes a long time to wake. To be fair the slowness is likely due to old fashioned hard drive that always gives you time to ponder the finer things in life.
I've got a MBPr and its worse than your situation. Reinstalled 3 times to see if it helps. So when it suspends and i open it up very soon afterwards i just get a blank screen for 30-40 seconds. I've learned to wait but sometimes you have to press keys to get it to wake up. Sometimes you press the power button. Then as you type your password it suspends again.
All because they don't want a sodding LED on the machine
From what I've heard it's because Macbooks have really aggressive hibernation(I've experienced this on my MB Air personally). Basically they will copy everything from the ram to the SSD and shut down fully. Then when you wake up it copies everything from SSD back to RAM - but if you have 16GB of ram, then even with an SSD it will take nearly 30 seconds to copy everything back, and until then the machine is unresponsive. I think it would be better if they just told you they are doing it "please wait, waking up", instead of just giving you a blank screen.
I'm very careful to not plug in an external screen before the MBP wakes up as your MBP may crash. Have made that mistake myself a few times and am nowadays very careful to first wake up the MBP before plugging in an external screen.
As does mine, sometimes when I just close it rather than suspending first it doesn't wake up and needs a hard reboot. Other times it needs quite some time before letting me enter my password and acts frozen until then.
Granted, the problem is likely related to age and failing memory (one of the slots is dead) but I do certainly think about suspend behaviour.
If I didn't know better I'd say it's almost as if maybe the user knows better whether to suspend or hibernate, and conflating the two is a classic "Apple knows best" pitfall they return to over and over.
