I always found that the easiest part of Zerg macro was producing hydralisks with 4sh5sh6sh etc, so I based my larvae layout with this in mind. Because I no longer need to use 2 keys on the left side of the keyboard when morphing larvae, I can start my buildings at control group 5 instead of 4, and my scouts/harass units on 4 and 3 instead 3 and 2.
I know pressing the same key is slower, but I find 5ss6ss7ss just too convenient to ignore. This also makes the rest able to fit into a 4x2 grid, with the most common morphs (ovi, ling, hydra, muta)
Select Larve: S
Abilities are all grid-mapped to Q, W and E, and R for burrow/unload (Load is F), since I almost always map my main army's spell units (including Lurkers) to 1 or 2. I tried messing with Attack, but I found it messed with me too much. Patrol I've set G so i can easilty switch between it and Hold during muta micro, and it's where I would make zerglings as well, with T for mutas right above (very handy in ZvZ).
Upgrades are also set to the QWE grid, mainly since I just never memorized them. It's also niceif you like to put your tech building on 1.
Buildings are based around the thumb on B and V.
The tech is in order of typical progression on the keyboard. A is for "defence structures", and Hatcheries, of course, have a special place at T (they are the best building in the game after all )
Spawning Pool: W
Queens nest: W
Lurker morph, Guardian/Devourer, sunk/spore, Lair/Hive are all mapped to Z and X. Out of the way of 99% of actions, but still easily accessible.