I find that bar end shifters work great. However when I switch from my single bike (brifters) to my mountain bike ("rapid fire" shifters) to the tandem (bar-ends), there is a very brief period of re-orientation.
Also, if you use standard drop bar brake levers with V brakes, you'll need to either use Travel Agents for the brakes or find some Dia-Compe 287V levers (what we use) to pull enough cable for the brakes.