- Regretfully decline the offer. Be gracious and courteous but direct. Language such as "I must regretfully decline" or "I am unable to accept" works well.
- Do not say you have received a better offer. Rather, indicate a neutral reason for your decline.
- In your case, something like this might work: I regret to inform you that I am unable to accept your employment offer at present. As you noted, this role will demand a fair amount of travel, and I am currently unable to accomodate much travel in my family life. With an opportunity to make suitable arrangements within the coming months, however, I believe I might be able to accomodate the degree of travel you require a little later this year. Thus, if it is agreeable to you, I would very much like to stay in touch with you in the event my situation changes in the coming months.
- Indicate what you most value about the company and the opportunity they extended to you.
- What is it about them or the job that most interests you?
As you can see, this is a simple and brief letter, with an emphasis on warmth and relationship management. Keep you content authentic and it will do the job for you!