To the OP:
Modern aircraft are very strong and have much better weather radars these days. Pilots don't like turbulence either - it is uncomfortable for us too and it spills our coffee - so we will do all we can to avoid it or get away from it. CBs are potentially very dangerous and we keep at least 20nm upwind of them and avoid flying over big ones, or under them.
100nm might sound a lot, but is not that far in big jet terms - it is only about 12 mins flying time at cruising levels. Turbulence can be felt 100nm downwind of a big CB.
Decent crews and decent airlines will take account of actual and possible weather on their route and will take extra fuel to allow for the extra flying miles of CB avoidance. So I would echo what derfred says; chose an established airline with good standards and a good track record, NOT the one offering the cheapest tickets.