In order of preference:
Use the can at home
Use a one-holer can while out
Use the less popular can if you must (some bix-box places have a front restroom and a back restroom)
If you must use a restroom while out and about ...
(and you usually will, we can't all only go #2 in our undisclosed locations behind blast doors and booby-traps)
... Here's what I do:
Use a largish stall, and carefully undo your belt**/pants. Lower them below your hips and re-buckle the belt. Lower pants and hold in place with spread legs or by hand. If you're paranoid or have biggish gaps under the stall walls, or are somewhere with a lot of kids*, lower your underpants in a way that covers the gun. Your gun is now safely in the holster, in a only slightly awkward reach, and still 100% under your control.
Taking the gun out of the holster has a lot of drawbacks, the biggest being that you end up handling a hot gun with less than complete attention. If you can easily dismount the entire holster and set it in your pants/coat pocket/whatever and still keep it under your control, that works. The family restroom might get you a funny look, but if the changing table is in a non-cramped spot that you can't miss on the way out, then it might work. Setting your gun on the toilet tank, in the plumbing, on the TP dispenser, or anywhere not under your control and not 100% guaranteed to be spotted on your way out is a recipe for embarrassment at best. Fumbling your gun while you try to do other things is just plain unsafe in the first place, and quite frankly after I'm done "making a log entry" I don't want to touch anything but the stall door on my way to the sink to wash my hands. I don't think my gun will catch something, but I don't want to be wondering if I need to sanitize it or something, and I handle that leather/Kydex/steel device a LOT without immediately washing my hands in the course of getting dressed in the morning and putting my gear in standby when it comes off of the pants.
*kids are lower down, pay attention, see everything, and they speak up without reservation
**This only works with a real gunbelt, one that makes your waistline stiffer as well as tighter. It won't help with a department-store "just makes pants tighter" belt. A good holster with wide belt attachment points helps, too.