There are two items to discuss. One is how to use the lights, and second what style light is best for ones needs.
1. How to use lights: Never use the blinking feature on the lights. Research has shown that people stare at blinking lights, and their cars will follow their line of sight. In short blinking lights will attract cars, so they get closer to you. Keep it on a solid beam in the front and rear lights.
Safety is important, but it is also important to save battery power especially if you don't have a stable place to recharge the battery. You should turn on your lights whenever you think it is comfortable.
2. What lights to buy:
A. On my last bicycle tour I used a Knog Frog, the smallest light on the market, for a night ride from Austin to San Antonio. It was not ideal, but it worked. I love the Knog lineup the lights are waterproof, lightweight, well designed, and have run times of over 100 hrs. The battery lasted the whole trip and alot more. Overall I think the Frog is a great backup on a tour, I would not recommend anyone use that as their main light.
B. Dyanamo lights: Dynamo lights use electricity generated by magnets in the hub. The lights work great, however they have a reputation of created too much resistance. I would recommend you stay away from these on a tour.
C. Magnic Light: This is a new product. the company claims that it is the worlds first contactless dynamo. Buy it if this works as advertized, it is the best solution for a tour. Read more on their website, it is very impressive.
D. USB Rechargeable lights: This a very competitive market, all the major companies have great offerings at competitive prices. Shop on amazon to see reviews before you purchase.
E. Solar Charging lights: These seem ideal for a tour, and they were popular 5+ years ago, however they are very difficult to find now. It seems the market has moved to USB charging.