A little more information is needed. What is your budget? Secondly, a good way to figure out what will fit in a fridge is to take your groceries to a store where they have the fridges you are interested in on display. For instance, if the Miele is of interest, find a Miele showroom, run to Costco and pick up your standard groceries, drive over to the Miele showroom and take it for a test run. No one will look at you strangely, I promise. This is really one of the only ways to figure out if a fridge works for you or not. The same advise is applicable to dishwashers except to take your dishes instead of groceries. In my current kitchen, I have a 30" liebherr fridge freezer and a 18" Gaggenau freezer. I love the Liebherr and I wish Liebherr made a 30" all refrigerator. I don't like the 18" Gaggenau. I realize once owning the Liebherr that I detest freezers with compartments on the door. My Liebherr freezer drawers hold alot more than the Gaggenau does. Liebherr sells an all freezer unit (they also make the Miele 24" freezer) and I am considering that. I was able to try out the Liebherr 24" freezer drawers at a local Miele design center because the staff fridge/freezer is a 24" Liebherr. I will probably upgrade to a 30" Miele all fridge in the near future.

Good luck with your decision journey!

They WILL look at you strangely, as I've done this, but it's well worth the stares! Would you buy a car without first test driving it? If you transported dogs in it, would you not take your crates with you for that test drive? At least this was my thinking!

A family of 4 who shops in bulk will still need a 2nd refrigerator unless there is room for two side by sides, one all freezer and one all refrigerator. Few kitchens can accommodate such, thus the need for a 2nd for "extras" elsewhere.

When I did my "test drive", I quickly realized that I need a side-by-side as I have a LOT of small bottles of condiments in the door and I need a full-length door. I also realized that I did not like bending down and searching for things in a bottom freezer. But that's me and everyone has his own preferences. Today's refrigerators are made for families with multiple gallons of milk in the doors, and multiple frozen pizza boxes in the freezer - just look at the photos of them filled. I do neither so I choose a refrigerator that met MY needs. Do the same for your family but don't forget that 2nd refrigerator unless you can do the two side by side.

Everyone is different, but here's some examples of considerations on refrigerator/freezer size:

1) Entertaining - some people need space to keep food for large parties of 10+ people. A friend of mine routinely hosts 50 people in his home using two 36" LG refrigerators. Every square inch of those refrigerators is filled.

2) Beverages - they take up a lot of space. If every family member has multiple chilled beverage preferences you almost need a separate refrigerator for beer, soda, juice, and water.

3) Leftovers - some households cook on the weekend for the entire week including lunches and dinners. Other households rarely keep leftovers.

4) Bulk - Costco, side of beef, hunting. You'll need more space.

Ideas:

36" standard fridge recessed into the wall so that it doesn't stick out as much into the kitchen. This will likely be the lowest cost option if you have the space to recess into the wall behind the fridge.

42" or 48" built in (such as Sub Zero)

Columns (such as Thermador or Miele) - gives you ability to choose dimensions if you need a lot of space such as a 24" or 30" wide fridge with a 24" wide freezer. This will probably be the most expensive option and take up the most space.

Frigidaire/Electrolux fridge/freezer pair - Takes a lot of space but much less expensive than columns. Downside is they are not a standard size and may be difficult to replace in the future if you want a built-in look.

There are 22cf counter depth units around.

You've all given me a lot to think about. Thanks!
We have a second refrigerator now and we're going to get rid of it. But now I hear you all make the case for it and it makes total sense to keep it. We'll just move it to the basement.
So that takes the pressure off the space issue.
Our budget is fluid - for now. It's been more a philosophical debate about style - we love the Miele and Liebherr - or practicality, as in getting a 25cf GE. Unfortunately we can't go wider than 38".
Keeping a second fridge means we can get the Miele if we really can't resist!
Thanks all