Is it worth it? Depends on you. For me, yes. The difference between lower and upper is simply how high you are and thus how much you see. You can see farther, generally, with the upper view, but I'm not a big fan of heights so I don't care about being way up there. The difference between resort and pool view is resort is on the DTD side, so you see that area. Resort view is only (I'm pretty sure) in the Dreams tower. The pool view is on the other side of Dreams and on the front of each of the Magic and Wonder towers. In Wonder, the pool view would be a higher floor because on the lower floors there are things that would obstruct the view. The back side of Wonder is a parking lot view and the back side of Magic is parking lot as well, but there are other nicer things to see on that side (like fireworks and part of the park).
If you request resort view, you will be in Dreams tower. However, I don't think they guarantee resort view--only resort/pool view, meaning you get one or the other.
If you go concierge, request Dreams tower as that is where the lounge is located. I think it would be a pain to have a concierge room in another tower. I don't even want to be on another floor!