I did a Linex under the rail with stainless rail caps. Matched my silver to the point that they are invisable almost.

 

Two of my friends regret using the "do it yourself" stuff. Doesn't hold up and tough to make it all look even

I have the Line-X over the rails and love it. On my old truck I had Dee Zee diamond plate rail caps. They looked good for a couple of years but the clear coat failed. Looked horrible.

Line-X all the way

 

I used the hard black plastic over the rail protectors.Was talked out of the metal ones as they mostly dig in.I also used the chrome/stainless pop up tie down inserts that go in the square holes in the top of the bed.Mainly to help keep the hard plastic protectors in place(they have a adhesive backing)I also have used bedmats last 3 trucks.Easy to remove and clean under the bed.Its a truck bed and the damage it will get on the wheel wells and inner sides is like OH WELL.The above route cost a fraction what a spray in costs and went to buy step ups and tool box etc.The DO IT YOURSELF roll/brush in liners I've seen used on Jeep floor boards and one truck bed looked BAD/POOR. Even the owners said it looked like hell.