Shelf project question

The wife has requested that i make and put up some shelves. First shelf will be a total 17ft long with 1 45 degree turn 10ft 1 wall 7ft the other, the second shelf will be 35ft long with 1 45 degree turn 24ft 1 wall 11 ft the other.

What is the best way to join the boards (1x8 pine) and or hide the joint seams? Ive found corbels/sconces that will work for the corners but lack experience and knowledge to join the longer (24ft) run.