We used to say "Allahu Akbar" when ascending and "Subhan Allah" when descending.
كنا إذا صعدنا كبرنا، وإذا نزلنا سبحنا.
Bukhari narrated it in the Book of Jihad and Expeditions (2993), from Muhammad bin Yusuf, who said, Sufyan (that is, Thawri) told us, from Husayn bin Abdul-Rahman, from Salim bin Abu Jaad, from Jabir, and he related it.