When planning a trip, you should consider the wishes of the whole family.
Literal
Trip [object-を] plan-do case [topic-は], family all-members [possessive-の] wishes [object-を] should-consider.
~場合は (in the case of / when) sets a conditional context more formally than ~とき. 考慮すべきだ uses べきだ (should) for a moral/practical recommendation. 家族全員 (all family members) emphasizes inclusivity.