A very good question. Here are my typical CW QSO exchanges. You - being in the US - will probably drop the “/P” suffixes.
[Starting up or when chasers run ‘dry’]
Me: cq cq sota sota de g8cpz/p g8cpz/p k
[Pile-up starts]
Chasers: (lots of chasers, I copy ik2ley first)
Me: ik2ley ga fabio ur 429 429 kn
Chaser: ga andy 559 559 k
Me: rr tu 73 de g8cpz/p ee
Chasers: (pile up again)
[S2S caller]
Chasers: (lots of chasers, I copy hb9cbr/p first)
Me: hb9cbr/p ga ur 539 539 kn
Chaser: ga 559 559 ref hb/be149 hb/be149 k
Me: rr my ref g/ld052 g/ld052 ok? bk
Chaser: cfm tks s2s 73 de hb9cbr/p
Me: rr tnx s2s 73 de g8cpz/p ee
Chasers: (pile up again)
Note: in EU at least we tend to use “s2s” only during the thank-you over.
Some smarty-pants will tell you, one can do the QSO with fewer overs or miss out some of the phrases but I think the above protocol is the right balance between clarity, courtesy and brevity.