I get motion sick on motion simulators, can’t ride Star Tours etc. My DH and DDs (13 and 11) can ride every ride at DL, including all the motion simulators multiple times in a row. We recently did a one day trip to USH on our January DLR trip specifically to visit HPW. I bought the unlimited EP (front of line for all rides as many times as you want; the regular EP is only once per ride per day and I wasn’t sure how many times they would want to repeat rides, price difference over regular EP was $40pp for unlimited EP). I could only ride the small ride in HPW, and after 2 rides on the big ride in HPW, rest of my family was a little unsettled. We went on, and they rode Mummy and Simpsons. After that, they were all very motion sick, rode big ride in HPW one more time since it would be our last, and we ended up not riding any more rides. I was surprised as they all ride everything over and over at DLR and have no issues (same at our local Six Flags and when we went to Busch Gardens in Florida, nothing bothers them). I think it is just too many motion simulators all at once. Due to space limitations, USH has no room for real rides.
I think you will be fine on the little coaster in HPW, but literally almost every other thing is a motion simulator. The other thing the EP can be used for is shows, for priority seating, so if you plan to do those, it might be worth the one ride per day EP for all of you. Note that the shows all seem to happen at the exact same time, so we could not see several shows in one day without staying very late into the day, which no one felt like doing after all of those rides (and we tried to do the rides early in the day prior to eating lunch to have the least chance of motion sickness, but alas it didn’t work, but that only left afternoon for shows). I think EP also gets you priority on the Studios Tour, so that can add value to the EP for all of you if that interests you.
If you can’t do Star Tours, you will have only 1-2 rides at USH. So only you can decide if it is worth it for you all. If your daughters are big riders, the unlimited EP might be a good option (the option to buy it only comes up on their website after you choose the regular EP ticket, then it pops up and asks if you want to upgrade to unlimited EP for an upcharge (ours was $40 pp at peak holiday time)).
USH was one and done for us, and frankly ruined the evening at DLR that we had that evening. I had us all scan into DL that morning before heading to USH so I could book all these evening FPs on MP from my phone while at USH waiting for them to ride. So we had awesome FPs set up at both parks that evening, but no one felt well enough to ride much after we got back from USH! Bummer.