What’s your best advice on what to do with 950,000 Citi miles?

In general, as long as you are redeeming for business or first class saver rewards, it will be worth it. This assumes you want to travel to London directly and experience SQ specifically.

Do note that SQ flies 4 times to London and hence the seat will be different on each flight.

If not, do note that CitiMiles have the widest range of transfer partner and you can also transfer them to British Airways (direct flights to London) or a variety of other airlines such as Cathay and Etihad, all of which have flights to London but will involve a stopover at their hub airport. This can be useful if you wish to break your journey up, or experience the facitilies at the hub airport.