A mtn bike crankset has been mentioned and thatd be paird with mtn derailleurs.

I diverge a bit from that, but i also dont ride thru mountains. If i had the interest and time to ride across the country or continents or whatever, i would not use what i currently use.

I like 48-38-26 triples. These are incredibly common on ebay as cranks from 20-30 years ago were set up for gearing about this type. You want new, which is understandable, so look into Sugino cranks. XD500, XD600, and XD2 are a few of the common typed you will see online.
The 26t ring can be swapped out for a 24t ring very easily and for about $15. That gives you even lower gearing.

Pair it with a Sora triple front derailleur or something like that. IRD makes a nice FD for these types of triples, though expensive.
The rear derailleur can be a Deore long cage or if you are willing to go used, a Deore XT long cage thats 9 speed or less.

9 speed mountain rear derailleurs work perfectly with road shifters and give you more chain wrap as well as a higher large cog in the rear.

The Sora FD is basic but it has the range to shift the setup and its a front derailleur...there isnt anything elegant to what they do. They shove a chain back and forth.
It wont shift like STI, but you also get gearing that(for many) allows for comfortable riding.


The shifter types i mentioned earlier- bar end, gevenalle, or downtube will all handle sifting very easily.

This isnt as tidy and elegant as all tiagra and STI. But its an approach that will get the job done with comfort.

I like the triple crank setup i mentioned because i can still ride the 48 ring when my bike is unloaded or when im with the wind or downhill. A 44-11 setup, i think i would spin out more often and be annoyed.

I just received gevenalle shifters last night for a bike im building (not touring). They are really cool and unique. Just food for thought.