Lucy about every 3-4 weeks. She gets groomed every 6 or 8 weeks, and we usually give her a bath between grooming appts.
Juno... meh, whenever I feel like it. Usually only when she's dirty, or when I feel like it's been too long since her last bath. She doesn't really get bathed in the winter, but they happen more frequently in the summer due to jumping in dirty ponds, getting slimed at the dog park, or running through a mud pit.