I find Samba one of the hardest dances to lead since the lady is away from your frame or body on lots of figures and the music is very fast. It's easy for her miss a lead. Samba locks, Promanade runs (with qqs or 123 timing), and Open Rocks.
You have to precede and follow each figure with specific figures or it wont't work. Plus, there are all the rhythm changes from one figure to the next. Unless you have a very seasoned lady that knows all the syllabus inside and out you are going have problems when you use anything but very basic figures.
If you want to be adventuresome, try doing Cruzado Locks with a inside and outside spin the lady on the qq's. Slavik and Karina do it on their latest dvd. I have done it with my teacher, but not with anyone else. Or try leading this with someone you haven't danced with before.
Samba in someways is very choregraphed with all the precedes,follows, and constant rhythm changes.