My pantry and MANY others are shown and discussed in the linked thread in the Kitchen Gallery. I am very happy with my shelf spacing...Some (about 14") to fit taller things like bottles, cereal boxes, and small appliances, and the others (10" spacing) for dbl stacks of standard sized cans. I have a 19" space at the bottom (floor level) for some roll-out bins I got. Best wishes!

Here is a link that might be useful: Pantry thread in kitchen gallery section

My pantry is also in the thread RHome410 linked above.

I have a small corner pantry w/shelves on two sides. The longer side has 12" deep shelves and the shorter side has 15" deep shelves. 12" deep shelves are fine for the majority of things, including small appliances.

As to shelf spacing, you can see it in my thread. Most shelves are space 12" apart, but one is 16" apart as I was originally gong to put a small MW in the pantry (it didn't work out b/c of the MW door swing and the small size of my pantry). The top shelf on one side is 19-1/2" from the ceiling for tall cereal boxes or anything else tall; on the other side the top shelf is 8-3/4" from the ceiling...it holds rolls of paper towels on their sides so they're easy to grab. The first shelf on both sides is 20" off the floor.

Here is a link that might be useful: Thread: Sharb-inspired Pantry Done!

You're doing the right thing by measuring the stuff you want to put in there. Once you get the standard cereal packets, your most used containers, cans and jars measured, think of the odd stuff that may end up in the pantry because they won't fit anywhere else - sacks of pet food, large bags of flour or sugar, things in large buckets. Those are the critical things to measure.

You can also go with adjustable systems where you're not wedded to your original measurements.

Whether you go w/fixed or adjustable shelves, I recommend they not be the wire type. Solid shelving is easier to keep clean and is easier to store things on. There's no trying to balance smaller things just right on the wires. If something spills it will stay on the shelf it spilled on and not fall through all the shelves & items on the shelves below.