Our itinerary is coming together. 5 nights west coast. 2 nights volcano. Is Hilo recommended to stay, what activities? or should we keep the second night in volcano?
I would not split your east side stay like that. It's a lot of packing/unpacking for no real benefit.
If you've already got reservations in Volcano, stay both nights in Volcano.
Or you could consider staying both nights in Hilo. They're not that far apart so it's kind of a six of one/half dozen of the other situation except Hilo has more restaurants, etc and would be a bit closer to sights along the Hamakua Coast.
I would just stay in Volcano. Using Hilo as a base to visit VNP isn’t great, staying near the Park also gives you more flexibility in being able to see Halemaumau. A lot of times when we’re there it’s not clear enough to see anything the first time we try and we have to go back later in the evening. Having lodging a few minutes away makes that possible.