Design of a hypothetical health insurance plan?

Let’s pretend that there is a government sponsored base healthcare coverage plan that covers child health issues through age 18-check-ups, immunizations, and any issues present at birth. For adults, all wellness services are covered, immunizations, basic hospitalization, etc. is covered at a coinsurance rate of 70/50 with a deductible of $1500 per person. The cost of this insurance is $50 per month covered family member.

Companies are able to offer a menu of “add ons’ to a basic plan. What type of additional coverage would you want to be able to purchase? (Such as allergy coverage; mental health, weight management, etc.)