During travel I use a padded pouch taken from the Nikon "Domke-lookalike" sling bag and put my equipment into my deuter 60L backpack. Its sealed so putting base of silicon pouch will keep the equipment nice and dry.
At the venues of interest, I used a Lowepro Photorunner to store my DSLR w an 18-200 zoom lens, a 50mm prime, and a flash. When I get a ultra wide, it will switch with the 50mm, depending on the aim of the shoot and the equipment I think I will need.