Here are a couple of websites I use:
Data Hub for all the World’s Airports - World Airport Codes (world-airport-codes.com)
This site has Airport codes Listed by
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Airport Code
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Airport Name
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City Name
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Country Name
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ISO Country Code
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World Area Code
Another site is:
Airports in the World @ OurAirports
With a database of 62,238 (presently) airports sorted by popularity or A-Z. A filter of airline destinations is also available.
For me, the problem is not deciding where to fly, the problem is MSFS.
When the official announcement trailer for MSFS was presented on June 19, 2019, I was thinking ‘finally immersion has reached new heights’. Back then I developed several of my own specific things to test, in hope to be on the test team. I also developed several lifetimes of flights.
Well I was on the test team, no matter, even up to this very day there are just too many bugs present; airports missing, aircraft systems broken, ATC broken still, workarounds galore, and CTD’s!?!
Deciding where to fly for me is never a problem, but when the sim is hit or miss, and mostly miss, I avoid frustration when I can. Until MSFS comes out of alpha I will wait…“wait”, the singular, one word description of homebased flight simulation. 
Of late, I know for sure this is still a pre-alpha product, there is no other definition. This is what makes it difficult for me to decide to fly at all.
I have been ready to fly in MSFS, and I will see how this new World Update (today?) goes, I will also wait and see how Sim Update 3 goes (wondering if it gets delayed too). If I see satisfactory progress in destroying CTD’s and bugs, I may just buy MSFS and finally fly, I have many hundreds of thousands (perhaps millions) of flights lined up…but I wait. 