36inch counter depth (builtin or not - you didn't specify) is not a lot of space for a family of 5. If you get a combined fridge/freezer, you lose extra space for the partition and the extra electronics. Space-wise, it would be more efficient to put in an all-refrigerator in the kitchen and an all-freezer in the garage, then a combined fridge-freezer in each location. It would also allow you to store wide items in both the fridge and freezer. That might also be less expensive because there are many inexpensive all-freezers and a freezer in the garage does not need to look fancy. Whether this works depends on how often you need to get into your freezer. The other consideration is that you probably don't want to have to go into the garage for ice. If you have a separate ice maker or a freezer drawer with an ice maker, that would solve the problem.. You could put two freezer drawers or a combo unit (one fridge drawer and one freezer drawer) under the counter. If you have a separate ice maker, you could even put in a beverage fridge under the counter to free up some space in your main fridge.

We can definitely have an all fridge in the kitchen and all freezer in the garage (and access to our garage is from the kitchen so it is pretty convenient). I'm not sure what you mean by also having a combined fridge/freezer in each location - do you mean a full size fridge/freezer unit? This wouldn't fit in our layout. We only have room for 1 set of drawers in our kitchen - either all fridge drawers, all freezer drawers or a combo drawer unit (1 fridge/1 freezer). So... do you think a 36" all fridge with 2 under counter freezer drawers in the kitchen and then a separate all freezer in the garage would be ok/good?

By combined fridge-freezer I did mean a 36inch unit that contains fridge and freezer compartments. However, it sounds like the option of all-fridge (and freezer drawers) in kitchen and full freezer in garage will suit you better. You should have plenty of space. FYI, you are not the first to have (or contemplate having) such an arrangement. In fact, we are considering a similar arrangement ourselves.

What about a 42" Fridge/Freezer?

Why counter depth-preference, or necessity? This decision gives you not one but four different appliance to keep clean. I hope you have and stick to a chore chart for the kids. I'd opt for the all fridge in house...fridge freezer under counter and if you still need it AND your garage does not get crazy hot/cold extra something in the garage. The part that I did not understand about your narrative is that you shop twice a week and cook fresh...so why do you need much of a freezer at all. Running such an appliance in the garage can be costly and environmentally unfriendly...and it will need cleaning too.

A 42" fridge/freezer doesn't work well either as we would lose 6" from our pantry (which is currently planned to be only a 36" inch wall pantry with pullout drawers so we don't want to lose any space there).

Counter depth works better with our layout.

We live in California so the garage can get hot for about 2 months every summer (it is in the 80s and 90s those two months with about 2 weeks of 100 degree weather) - good point about whether a freezer in that location would be efficient.

Currently, we do not freeze a lot of food. However, its hard to determine how much space we need.

I'm leaning toward the 36" all fridge and the separate freezer drawers and adding a freezer in the garage if we feel we need more freezer space.

We are a family of two seniors. We have a 36" Miele with bottom freezer. We don't freeze a lot so that freezer is adequate for us. However, the fridge is tight and when we have house guests I could not really manage without the old side-by-side fridge in the garage. For a family with 3 boys I would definitely go with the all fridge plus freezer drawers. I also might get a basic utility garage fridge (about $400) with small freezer. That will be enough back up. Even for the two of us, the drinks take up a huge amount of space.

Why not post your plan and see if the gurus here can help get you more pantry space and a 42" fridge/freezer. They are the best.

i just posted the floorplan in a different post...

Addl things to consider. You will need lots of room for produce, therefore fridge space.

You can gain 3 inches in depth if you recess the main fridge. Cabinetry can be built around a cheaper and bigger main fridge. I bought a 25 cu ft LG fridge with 6 or 7 c. f. of freezer space, f.d. 4 years ago for about $1600. IIRC, it was not as deep as the big honking fridges, maybe 34". And our cabinetmaker built it in and our gc recessed the space into the studs, gaining 3 inches in depth. It looks pretty good. Also bought Elux fridge drawers then for $2000, now approx. 2500. It has and is serving us well. We also have an upright freezer in the basement. I will do the same here in our new to us Arizona house, altho this house is bigger.

Do a google search for recessing the fridge. Counter depth and built ins look good but you may find these 'tricks' I mention above will visually please you enough and give you the bonus of six more cubic feet of fridge space in the main fridge. With a growing family of three boys, I would explore even more space than you think you need.