How you use your truck is a very individual thing. You'll have to consider different scenarios and how you might use the bed. A cap might be great for you. It might not. It sound like you already have your mind mostly made up. :)
Our Sierra had a cap on it when we bought it. It was a very nice cap, but neither my wife or I like caps. Makes 'em look like work trucks. I toyed with the idea of using it because I really like the idea of having things locked and dry. I played with methods of hauling our bikes in it but it was a real pain to climb in and out of, not to mention removing the wheels and attaching the forks to the mounts. We also didn't like the lack of good visibility behind us.
We sold the cap and bought an Extang Solid Fold tonneau cover instead. The truck looks great, visibility is excellent. And I can remove the cover in 5 minutes to haul our bikes or other larger loads. The best part is that its secure and with a cargo bar, we can use the bed like a trunk most of the time.


