Having stayed at VWL a couple of dozen times over the past 15 years (it's my home resort), I can unequivocally state that on the lake side seeing fireworks and EWP is possible, especially the latter now that the cabins have been put in. I do agree, however, that at best, you will only see the higher explosions from the fireworks. And, you'll have to crane out a bit to even catch those. Still, it is possible as I have recorded said fireworks from a lake side room at least three times over the years and from as low as floor 3. As for EWP, many of the rooms allow for quite good views of it. Again, it all depends on your actual location--the closer to the main Lodge you are the easier it will be to see EWP as a general rule. Certainly, the higher you are adds another aspect, as well. In short, while I wouldn't expect to see great views of either fireworks or EWP, if you are on a higher floor on the lake view side of VWL, you might catch glimpses of the former and a great deal of the latter.
As others suggested, the Geyser Point area offers some fairly good views, and they pipe in the music. On my last trip just three weeks ago, I was able to see a great deal of the fireworks standing at the intersection of the bus stop and the stop sign just before heading to the main entrance of the Lodge. It's the point where you cross over to the parking lot from the bus stop if that makes sense. I got some great shots of the fireworks there.