I can cross 13 off my list - whale watch, safari, Aurora Borealis, paradise island, WW rafting, Route 66, elephants, motorcycle, waterfall, hike a glaciar, rollercoster, Disney World and Vegas.
If only 5 more: swim with Dolphins, go to the Galapagos, see the Polar Bears, try the Crested Run and bungee jump from the Sydney Harbor Bridge after I've clilmbed to the top (can you see Uluru from there?).  And of course I would take the Rocky Mountaineer, the Orient Express and the Trans-Siberian Railway whenever possible.