I see two different companies offering this type of service and was hoping for some input regarding either or both.
Parisopentour.com is one. It has 4 different lines. My question is (and I couldn't find the answer on their website), for the ONE day pass, can you use one or all 4 of these lines if we so choose? I can't imagine doing so but the buses run from morning to night and I was wondering if that one day price included any and/or all of the lines.
The other bus I saw was Big Red Bus. This looks like it only has one route and hits many of the POI. It is only a few euros cheaper for the one day pass.