I have Elfa ventilated shelves (and some drawers) in my pantry and laundry room both. I love them BUT I use liners so I don't have the wobbly issue going on. That would drive me crazy. Elfa's ventilated shelves, unlike what you can find at Lowe's, HD or Ikea, have the wires a lot closer together. They also "lock" into place so the wire part is sitting really firmly in the bracket - not just a piece of wood sitting on top of the shelf bracket. As far as organizing little things, Elfa has "shelf baskets" that you can put dividers in and stack stuff in if need be. In the pic below, I have one of those on the immediate left (3 shelves up) and above the counter top oven in the back. I use it for bags of baking stuff like chocolate chips, coconut, etc on the left and treats in the back. And I absolutely love their big drawers. Container Store's return policy is great too - anytime with a receipt and the best Elfa sales is 30% off all Elfa products. It starts Dec. 24th and goes through the end of January typically. There is one in the fall that isn't as good - 25% of Elfa Shelving. (No, I don't work for Container Store, I am just a big fan and will be buying some more Elfa stuff during their Dec. sale.) Here's a picture of our new pantry.

I had a walk in pantry that was about 7 feet deep with narrow shelves along one side and slightly deeper across the back. It was across the hall to the garage from the rest of the kitchen and it was a pain. It looked great when staged for selling the house, but it didn't work that way. My pantry here was in the kitchen proper -- a step-in across a corner. That was better for convenience, but the shelves were only across two sides and nearly half of them got lost in deep corners. I tried trays and baskets to keep things organized, but it just didn't stay organized. My kids would throw things back in and it seemed we were always loosing stuff in the back or underneath. The dog food and drinks that went on the floor somehow gravitated out to the step-in space at least at times. The shelves in both of these were fixed and the function could have been improved by ripping out the shelving and reworking things, but never had the chance at the last house and we decided to take out the corner pantry and replace with cabinets. It really opened up the kitchen space, so we were happy about that. We'd had a 24" pantry cabinet that came with minimal shelving before and we knew we didn't want that. We did the rollouts for dry goods (boxes and bags) and a pullout tower for cans and bottles. My spices went into a drawer. It seems to be more efficient - easier to see what I have and to get to it, better turn over of staples, and most of it stays better organized. I don't have to straighten them too much -- just the bread and snack drawers at the breakfast hutch, and they are much easier because they are not too large and I can easily see and reach everything. Never underestimate the value of full extension glides. LOL

I think you are thinking this through well. I would put the deeper shelves in the middle (easier to see and get to). Measure what you want to store in the pantry and make the shelves deep and tall enough for that. I stored lots of can goods in my last pantry (in the boxes they were sold in) that fit on an 11 in deep shelf. My newer pantry had shelves tall enough to use a canned goods storage container that works better. I had shorter shelves for foil and plastic wrap and sandwich bags. I store paper towels on the floor along with grocery bags. We used quality shelving in our pantry and it held up really well.

I'll add here that while the idea of removing or moving the fixed shelf will work as long as the cabined is supported on both sides, it is not really necessary. We just completed our kitchen. Pantries were two 24"x90" high with drawers for food and one 15"x90" high as a broom closet. The default location for the fixed shelf is 60" which is plenty of height in my experience for mops/brooms. The 60" door is the tallest that Ikea makes, so while you could move the shelf up it necessary, you won't have the shelf providing the split between the 60" door and the 30" door above it.