This award space from Miami (MIA) to London Heathrow (LHR) is pricing at 57,500 AAdvantage miles in business class. At last check, only 3 seats were available at this rate. Keep in mind that taxes and fees run $738 on top of the miles, which is standard for award tickets departing to the UK.
For context, business class awards on this route typically price around 115,000 miles through American's dynamic pricing. That makes this redemption about 50% cheaper than what you'd normally see—a solid value if you have AAdvantage miles to use and the travel date works for your plans.
One practical note for families: with only 3 seats showing, this works best for solo travelers or couples. If you're traveling as a larger group, you'd need to search for other dates or consider splitting the booking across programs. Also factor in that $738 per person in fees, which adds up quickly for multiple passengers.
April 1 falls during the UK's early spring shoulder season, so you'll find moderate weather and fewer crowds compared to summer travel. It's also during many US school spring breaks, which may or may not align with your family's schedule.
How to book
Search and book directly through American Airlines: https://www.aa.com/booking/choose-flights/1