My wife has just entered the third trimester. Would you have any suggestions for her overall well-being? Also, what would be an ideal midnight snack?

Just keep her relaxed, happy and healthy before she gives birth :) Also, if there are errands that needs to be ran before the baby comes, help her out with that cos it will probably be difficult for her to move around like before. As for the midnight snack, opt for something protein rich as this will keep your wife full all the way till morning. Try foods like low-fat yoghurt, nuts, whole-wheat toast with peanut butter, turkey sandwich on whole wheat bread.