Yeah, the AC games don't have much replay value, Batman isn't much better which is why I almost never buy SP only games. Batman was fantastic though and there's a good amount of extra stuff to do.
I actually farmed the red chest on top of the roof a time or two and got a few good bits, I don't know where the other one is. And the white chests had mostly crap, the two I know of anyways.
The best stuff normally comes from the red ones, the best I've seen in a white box was blues & maybe a very seldom purple. Helps for the $ and there are those challenges that give xp rewards.
I ran them enough with my soldier that I've worked out a route to run and grab them.
It's easier to show but I'll toss this out:
White box - Facing the new-u pole looking into town. Turn left and go up the stairs, keep going and you'll come to a sheet of plywood over a gap that butts up to a wall. Jump at an angle to the left to get over the railing. Keep going straight while looking to your right.
Red box - From the previous turn around until you see the metal wall that has a little platform on it. There is a red tarp coming off of it. Jump on the wall and get on the tarp. Face towards the bounty board and look a little more to the right. You'll see the red box on a low roof.
White box - Fall down & it's in the room the clap trap opened.
At this point I normally hit the health vender than swing around to the gun vendor.
White box - Start by facing the gun vendor. Turn right and go a little ways then go up the stairs. At the top of the stairs is a washing machine. Jump on it and work your way to the roof. Go around the sat. dish.
Red box - From previous white box drop back down to where the washing machine is. With the wasing machine behind you jump at a little of an angle to the left landing on the roof type area. Go to the end and jump at an angle to the right landing on a metal roof. Jump over to the building roof next to it, than jump onto the taller building.
Also there are challenges that give xp rewards. Hit the back button & go to the list of missions. Hit Y and it will bring up the list & the ones that you have completed will have a check mark next to it.