Hope some of these spark your interest or get the name flow going
Aldric, Alden, Alaric, Atticus, Angus, Amadeo, Alcander, Ajax
Breccan, Braith / Braithen, Bennett, Bram, Blaise
Caspian, Conrad, Colby
Fallon, Finnick, Fabian
Geoffrey, Godric, Grover
Javier, Jacoby, Jotham (I worked with a guy named this and thought you may like it)
Kellan, Keanu, Kurt, Koda
Lachlan, Lysander, Leland, Leopold, Lazarus, Lionel
Remington, Rafferty, Rocco, Roscoe, Roald
Tomlin, Theron, Theon, Thorfinn, Tarquin, Tavish, Tobiah, Tiberius, Terrance, Travis
Wulfric, Wallace, Warren, Wilfred
I think Atlas or Orion would be great with North and Everest. My only hesitation is Atlas and North may seem too geographical together? On the other hand it would fit your subtle theme nicely. Either way, I still think it's a great choice. Orion's mythological connection to Atlas is also really cool and may be a more subtle way to connect to Everest and North.
Love previous suggestions of Atlas, Orion, Jasper, and Caspian!
My offerings are sort of all over the map…astronomy, nature, western, explorer, rugged sounds…anything I would pair with North and Everest.
Drake (as in Sir Francis Drake, the privateer/explorer)
Jack (I know it's quite simple in comparison, but North, Everest, and Jack just screams of rugged outdoorsy brothers)
Yukon (too theme-y?)
Forester (I thought about Forrest, but it's so tied to Forrest Gump)
Clark (as in Lewis and Clark…a more subtle tie-in to the explorer theme)
Colt or Colton nn Colt
Orson nn Bear
Ronan (means "little seal!")
I'm excited to see what you choose!
Frost comes to mind for me first, North and Everest both have an icy cool feeling to them in my opinion! I think the third name should match that!
To go with North and Everest:
I agree that Lachlan might be a great match; Logan, Landon, or Leland too. Lachlan would be my number 1, of the 4 choices. These not only seem to catch the same surnamey, very manly vibe, but as far as syllables go, all the "L"s that I've suggested are 2, while North is 1 and Everest is 3. Not a bad combo at all!
I'm curious to know what your other boys' middles are, especially with last name Joyce.... Yes, please keep us posted.
Such fantastic names your boys have. Truly. You've gotten a lot of great ideas here, too, many that I would have mentioned. Trying not to repeat suggestions, how about...
North, Everest and...
An observation: both North and Everest contain a strong R sound. It might be nice, subtle way to tie all the names together. On the other hand, if you are planning to have a large family, you might not want to start a theme of unusual names PLUS R!