We usually tip as a crew. One gets it arriving at the hotel, the other when we get dropped at the airport and so on. I usually do $5 for us both (or the foreign equivalent).

I feel maids should expect to clean my room once as part of their job. I tip maids if I stay multiple days and I let them clean while I’m still going to be there ($5). I generally try to leave it reasonable when I leave but if not, I’ll leave something.