GIven the multiplier (2x or 3x) promo going on for the rest of the year, I don't see any benefit to stays over nights.

The Milestones bonus is on nights anyway:

I have 35 stays and 38 nights and it says in my account:

get bonus points every 10 nights starting at 40
2 nights needed to get 10,000 Bonus Points


The only case where it would matter within HH alone would be if there were a promo that rewarded stays rather than nights, but that's not what HH tends to have as the promo in the last quarter of a year.

It might matter for someone who's alternating between HH and another program which does have a stays-based promo (and thus using HH for alternate nights), but that's a different situation than you're talking about, and anyway it would the other program "pushing" someone into doing one-night stays at HH in that case.

Btw, a reminder: Your profile at the left says you're still HH Silver.