After some thought, I think I've decided to go with $15/visit, an extra $5 per visit for special things (dog walking, difficult pets needing medication, etc), and $50 for overnights. Compared to other techs, and in response to the clients when I've asked for that, they think it seems fair and on-par with other sitters in the area with my experience and education (actually I've had someone say that $50/night is "very affordable" versus taking your pet to the kennel).

Thank you all so much for your input, advice, and suggestions