I've mentioned in other threads, we use to do rollercoaster vacations. Sometimes two weeks straight. I'd buy a SixFlags season pass and at the time, you could visit any SF for free. We did just about all the theme backs east of the Mississippi. We became pros at managing the crowds (we hated to wait in long lines).
But back to Universal. We'd hit City Walk when the crowds were in the parks (i.e. while everyone is doing the rides, we'd eat). Then when people are eating, hit the rides
Can't say I've done a lot at City Walk. Just meals and walk around the shops. There was a Lowe's theater if you want to catch a flick and get off your feet (don't know if it's still there). The HP area is neat just from the aspect of detail. Some of the rides queue areas are just amazing. That's the problem when the rides are walk on - you miss just how elaborate the queues really are.
You might already know this, but here's some tips: Get there early, and go to the back of the park first. Everyone is still up front working their way back. Then when everyone is in the back, head towards the front. Stay late - people leave early. We'd also go to the park during off times. How do you know when that is? When the airlines charge the cheapest rates to fly to Orlando. Universal is rather empty the weeks between Thanksgiving and Christmas, you just about have the place to yourself. But they close earlier too.
Have you seen the Christmas thing where they project images outside onto the HP castle on YouTube? Crazy cool. I haven't seen that in person tho.
Not sure if I really answered you questions. Most their rides are top-tier. Eating the the Jurassic Park Visitor Center is fun - looks a lot like the visitor center in the movies. Not fancy food. Eating by the pond at Universal (not IOA) is nice too - in warmer weather. Nice views.
If I'm not mistaken if you buy a wand at IOA, it can be used to 'activate' different things at the HP area. But look into the details since I've never done that.