I have always planned meals a week in advance, even though some have to be re-arranged at short notice.
DH and I have always liked trying new foods, new recipes, new flavours. If either of us doesn't enjoy a new dish then the recipe gets chucked . If we both enjoy it, it gets added to my recipe list. Meal planning is easy because I am only ever choosing from recipes we know we both like.
On his own he varies in what he cooks or prepares for himself, tending to see what is available in-house and supplementing it from the local Co-op. Although going for a curry is an easy option if I am away.