I agree with those suggesting HRH. As Damo suggested, a Deluxe room would be best. Of the 3, HRH has the closest walk to the parks, with RPR not being much further away. Some people walk from PBH, but my family took the boats. It was a little too far for us to walk.
Chances are good that your 11 yr. old will definitely like HRH better. I think your 9 yr. old probably will too. Your 7 yr. old may or may not prefer the pool at RPR. Basically, RPR's pool is better for younger kids. The pool at HRH attracts older kids, because of the slide & the fact that "it's the happenin' place to be."

PBH also has a nice pool. They actually have 3, but the Beach pool is the one kids would enjoy.
All 3 of UO's resorts are Deluxe resorts. They're all nicer than any of WDW's mods. If you're looking for comparisons, RPR would be more similar to the Poly. The theming is similar. RRP's rooms are smaller though. RPR is newer & doesn't seem as dated as parts of the Poly, although the Poly is a very nice resort. HRH isn't themed similarly to any of WDW's resorts. If I were stretching for a comparison, I would compare it most closely with the Epcot resorts (not Swan/Dolphin). The only resort at WDW than can compare with PBH is the Grand Floridian. The rooms at PBH are larger than at the other 2 resorts. The beds & bathrooms are amazing! IMHO, PBH is a no brainer for 2 adults. However, with kids along, my vote goes to HRH.
I don't know how familiar you are with Universal, but the set up is nothing like WDW. You can easily walk from one park to the other. CityWalk connects the 2 parks. HRH is about a 5 min. walk to US. Add another 5 min. or less & you're at IOA. RPR is on the IOA side of the UO property. It takes us at least 10 minutes to walk from RPR to IOA. Again, you could be at US in another 5 min. or less of walking. We did find ourselves occasionally taking the boats to & from RPR. My health isn't good though, which doesn't help. The only way we would take the boat from HRH would be if we were looking for a change of pace. It's much faster to walk. FYI, the boats dock at the center of CW.