My preferred day is also Friday, but I have generally had to take whatever is available.
I would expectly monthly to be the most, less for biweekly and least for weekly.
I might also expect a higher charge for the initial cleaning. Mine charged 1/3 more for the initial cleaning.
Sometimes I consider moving her to weekly, but I think that would be somewhat harder on us (DH works from home) and it would also create more conflicts. Overall, I think every other week works well for us. Most people I know with cleaners have them come every other week.
When I had napping kids it was tricky around their nap schedule. But I would tell them to clean the baby's room last if the baby was sleeping when they arrived and generally the baby woke before they were ready for it. I also just had them skip the nursery once or twice.
Beth, mom to older DD (8/01) and younger DD (10/06) and always missing Leah (4/22 - 5/1/05)