We will have most of a day in Rio on our own after a full-day tour. But the guided tour won't take us to Sugar Loaf. Are advance tickets recommended for that in mid-March? Not sure when the best time to go will be......we are willing to buy fast-pass access, but don't know when to get them for!

Absolutely, purchasing your Sugarloaf tickets will always be the best decision. Especially heading towards the middle of March, the attraction will be busy. If your schedule is tight, definitely opt for a skip-the-line option to save some time. The beauty of Sugarloaf is often at its highest late in the afternoon and into sunset, so be sure to plan for early arrival to give yourself time to see everything before the sun goes down.