Is it better to have family member or nanny sit if mom and dad travel a lot?

Personal preference. You will need a reliable souce of childcare and a back-up plan. Nannies usually become almost a family member. Relatives know you best but can tire out. The most important quality is a loving attentive caretaker. Make sure your desingated sitter can seek medical attention for your child when you are away. You may find different solutions at different stages of your child's development.