What should we do with our grieving cat when we go out of town?

We unexpectedly had to put our older cat to sleep this morning. We're all in a bit of shock. But here's the challenge - we are going out of town next week for a week. Will it be too much to leave our other cat in the house by himself while we are gone, even if we have a sitter check on him every day? Or, should we take him on the plane with us? Which would be less traumatic for him?