I'd pick the ES Beachwalk all the time, every time over the HHV.

HHV = a tired old hotel crammed full of people, overcrowded pools, tourist trappy feel, parking far away, giant hamster maze, etc. Hated my last stay there a year or two ago, dirty rooms, old peeling paint, maintenance issues.

ES is across the street from that same beach, just on the quiet end of it.

ES = nice hot tub, free drinks at happy hour, great free breakfast, big newly remodeled suites with separate room for the kids to stay up and watch tv while mom and dad get a separate private room to sleep. Light up toilets! Shallower pool, but plenty fun to splash around in, and often less crowded than the HHV. We park in the hot tub during happy hour and kids can swim in the pool.

I've stayed there when my kids were younger, and we liked it much better than HHV. The only thing HHV had going for it was the little lagoons, but your kids are old enough that they're going to have fun wherever. Snorkeling most anywhere on Waikiki isn't as good as the North Shore Tidepools (best place for kids), Three Tables, or Shark's Cove (although it's high wave season up there right now...) so I don't factor that in too much. But ES is closer walking distance to all the tourist fun stuff than HHV is. Elevator down, turn onto the main street, and bam - marketplace, restaurants, main shopping strip, etc.

I'd say: Stay at ES, stroll over to HHV and check it out. You'll probably glean that you made the right choice. Either way, Hawaii beaches are public, so feel free to park your towels right in front of the HHV and watch their fireworks at night, then return to your non-zoo ES hotel.

Bonus: ES is right next to that military museum on the beach. It's free, kids might dig it. Neat dioramas, weapons, and history stuff.