Both Diagon and Hogsmeade have an Olivanders- with the new one in Diagon offering much shorter waits. You can also buy them at carts with no wait at all. But do the show.
Some great touring plans are located here:
http://orlandoinformer.com/universal/touring-plans/
My first experience I followed in Harry's footsteps. Yes, you wait a longer in lines. No, you don't get to ride a ride immediately. But it's extremely enjoyable.
-Start at USF and go to London and meet the Conductor/Shrunken head at the Knight Bus
-Eat Breakfast at the Leaky Cauldron (Like Harry and Hagrid did before shopping at Diagon Alley)
-Visit Gringotts Money Exchange and trade in those muggle bucks
-Do your shopping for school supplies (Olivanders for wand- we bought our robes on Etsy and Owl for kiddos on
Amazon)
-Visit Knockturn Alley
-Board Hogwarts Express
-Ride Harry Potter & Forbidden Journey (going to school) as well as Flight of Hippogriff and Dragon Challenge
-Have lunch at 3 broomsticks
-see frog choir and triwizard rally
-Grab some sweets
-Head bak on hogwarts express
-Ride Escape from Gringotts and face Voldemort
-Eat some celebratory Ice cream at Florean's while watching tales of bardlebee or celestina warback
Not the "smartest" touring strategy in terms of maximizing rides- but you could easily finish that by 3pm or so. And its unique and fun- and way more about the experience than "ride count".