You ask the same questions I had about gearing and all the above is good sound logic based around each person’s needs and abilities. For what it’s worth here is the logic I used.

After riding doubles and triples and experiencing the wider cassettes I was drawn to the triple because with the center ring in the center it gave me full use of all the cassette.

The question was for me do I want a close spaced cassette because I love the ability of fine tuning as mentioned above or do I want a wide spaced cassette that lets me stay on the center ring more.

The question was more compounded as I wanted to ride the bike loaded but also recreationally and as a commuter and I found my ideal range between the two was a couple of gear inches different.

When I looked at closer spacing on the cassette you lose the larger cogs and that causes you to need a very small granny gear for touring.

I found for me a 42t center ring with a 12-36 cassette covered all my needs except loaded climbing or steep unloaded climbing. I found a 30t granny was just a little too big for me a 26t was really nice and a 24t was amazing for climbing with lots of load.

At that point my answer to your question was I need two rings only but I can’t get them on any double crank spaced like I want with the big ring lined up in the center and a granny as small as I wanted. But a double on a triple crank was really nice. I thought about taking my big ring off all together and rode around for a year with a 52t big ring I never used. I thought about a smaller overall setup so I could use the big ring and tried a 44-32-22 mtn crank and liked the little granny ring and loved the way the 44t ring worked with the 3 smallest cogs (straight chain line) and absolutely hated the 32t center ring because I had to make that front shift part way thru my range. I just felt I was always thinking about where I was with the shifting.

That gave me the idea to try something like maybe having two rings nearly the same size or even the same size as the center and large ring. With playing with the numbers I found 45,42 with my cassette gave me a perfect third ring and half step shifting and the straight chain line on those small cogs. I now have filled in the wide spaces in the 12-36 cassette only when I need them with a simple shift.

So my answer to your question is like Nun said a double will do the job if you can get the rings you need on ether a double or a triple crank and stay away from cross chaining too much and make your big ring work with the whole cassette to give you an almost full range minus the granny range of gears. Or in my case a triple because it gave me everything I wanted in terms of spacing and minimal front shifting and a range of gear that cover both touring loaded and road riding unloaded. No one sells a bike remotely setup like mine and I have a big box of parts getting to where I wanted to be, but the final result is everything I wanted.