Is there any way to customize what buttons wake the unit from sleep?

Not sure what you mean by sleep: expedition mode, battery save mode, or button locks? Regardless, it's the power button. This behavior is by design. The point is to avoid accidentally waking the device while it's in your backpack (or anywhere else where accidental button pushes are possible).

Note that as long as the display is visible and the buttons are not locked, pressing any button turns on the backlight (and the button does not perform its normal function).

Thanks for the reply.

Battery save mode, to be more precise. My use case might be unusual, as I will have this mounted on a bike for navigation. I'll want to allow it to go into battery save mode, but finding the power button vs just tapping any button at speed when I can't see the power button will be a pain.

This is something that should be configurable.

I'd very much like this feature too. I have power save turned on to help limit the screen taking up battery while it's just clipped to my bag, but it's a bit of a pain to hit the power button every time I want to see the screen, especially when I'm actively using it and look away for more than 30 seconds. There should at least be the option to wake from any button or wake from power only so users can customize it. The screen lock could then additionally be used if someone is really worried about accidental messages or presses.

Hi, I know this is an older thread...but I would like that as well.  I understand the reason for the design, but the power button is not as easy as my Oregon 650 was to awake it.  What if you did something like a combination of two buttons ...Mark & -.  or allow user to configure which buttons.  Or hold a button for 2+ seconds...??  The reason is I am used to the one hand push on the side to wake up the Oregon and I have to just get used to a new unit.  I could put that to sleep & wake it back up with one easy push, and holding it with one hand as well.  But with no easy way to put the 66i to sleep, in order to save power, I have to let it go to Batt save mode in 15 seconds and keep hitting a key to keep it awake.  Because I sometimes just want to take a quick peak at the map and it kills me to know I have to waste power, waiting for it to go back down for a minute, if I set it for that long.  Should have put the power button on the side, or TWO of them like the 650 and the BIG >SOS button on the top! 

I would also very much like the option to be able to wake up the unit using one of the buttons on the front of the unit.

I'm mostly using the 66i on a kayak at sea, often one handed. Waking it with the power button can often be a challenge, it would be much better for my use case if I could enable waking it with a single press to one of the buttons below the screen.

It doesn't help that the power button itself is much harder to press than any of the other buttons on the unit, though I realise this is probably by design to avoid accidental presses when stuff into a pocket/backpack.

Although I'm sure using the power button is the sensible default for most people most of the time.

Piling on here won't get it done. Forums are not an official support channel, let alone a way to request enhancements.  Do so here:

https://www.garmin.com/en-US/forms/ideas/

The more people who suggest the same thing, the more likely it is to be addressed eventually.