Reddit reviews 100 Years of Harley Davidson

Here are the ideas I could think of:

1. Harley Davidson Gift; Like a Coffee Table Book ( https://www.amazon.com/100-Years-Harley-Davidson-Willie/dp/0821228196 ), maybe some nice HD-Keychains (https://www.amazon.com/s/ref=nb_sb_ss_c_1_25?url=search-alias%3Daps&field-keywords=harley+davidson+key+chain+gifts&sprefix=harley+davidson+gifts+key%2Caps%2C181&crid=SIS8J4QDX87F&rh=i%3Aaps%2Ck%3Aharley+davidson+key+chain+gifts ), Check out Etsy as well...lots of ides there too.
   
   
2. Create a Ride! Include a map with the details noted (Points of interest, Sight Seeing Stops, and Gas Stations and Stops for Food), And Include a Gas Card and A Gift Card for Lunch or Ice Cream somewhere along the ride. *I know you said that they wouldn't like home made thing...but this is Gift Cards with a Plan. It would defiantly take some effort on your part.
   
   That's all I got....Maybe if there are other people in the family, they might be able to give ideas of other things that the couple like besides Harley Davidson...Because sometimes people like to do something but they don't want their entire life to become that one thing. But if they really love everything Harley...then there are a lot of home decor things...Dish Towels, Welcome, Rugs, Key Hooks, Wall Art, Sculptures, Wood Carvings, Etched Glassware.

Whaddaya wanna know?

Books can help

http://www.amazon.com/Complete-Harley-Davidson-Model---Model/dp/0760303266/ref=sr_1_9?ie=UTF8&qid=1405429006&sr=8-9&keywords=history+of+harley+davidson

http://www.amazon.com/100-Years-Harley-Davidson-Willie/dp/0821228196/ref=sr_1_2?ie=UTF8&qid=1405428944&sr=8-2&keywords=history+of+harley+davidson