Aloha. I moved away from Oahu a year and a half ago after living there for 11 years. I have ridden every road on that island and on Maui and to some degree on the Big Island. Let me tell you, there aren't that many roads on Oahu and you will miss Colorado for the wide open spaces. BUT, the scenery definitely makes up for it. Ok, so here's some ideas:
1. Since you're military, you gotta check out the restricted road through KoloKole Pass out the back of Schofield Barracks. Only accessible by military and was closed for a few years after 9/11 but was open again as of two years ago. Beautiful. Kemoo Pub is the best biker bar on the island and is located in Wahiawa just outside Schofield Barracks.
2. Make sure you head out to past Makakilo/Kapolei to Makaha, the surf and views are unbelievable. A lot of folks are hesitant to go, but don't let that stop you. Also, if you're into 4 wheeling there is actually a great 4 wheel drive only road over that tip of the island.
3. There are a lot of nice side trips (although short of course) around Kailua and Kaneohe, you'll just have to explore. The Shack is a good biker friendly bar/restaurant in Kailua. Stop in at Prostreet Motorcycles in Kailua on Dump Road and say high to Deacon, great shop and great people.
4. For what its worth, Oahu isn't a long haul type of place, obviously. Bikers are more into profiling and cruising. Never underestimate how fun it can be to cruise Waikiki Friday or Saturday evening, park your bike at Sandy Beach and check out the scenery. I always had Island fever and had to get off the island for two weeks every year for some extended riding around the mainland
Its staggering how many bikes there are on Oahu. Every event is big and well attended. Make sure to keep a look out for the Toys for Tots parade as it is usually the biggest gathering in Waikiki. Also, the State Hog Rally is every year in Oct with pretty good turn out.
The biggest dealer and the sole Pacific distributor for Harley is Cycle City near the airport. South Seas in Waipahu is a little more down home, and Domenicos in Kaneohe is smaller still. I never had my bike serviced at a dealer, I used a guy named Larry at the Hog Pen. Great service and priced right. He is/was located with Deacon in Waipahu but may have moved when Deacon moved to Kailua recently. Anyway, he has a small shop and lots of people know him, I highly recommend him.
Too bad the super ferry isn't running anymore. It started after I left and is already defunct. That would have been the best bet for a "quick" weekend to another island for some extended riding.
Too hard to put it all in one post. You'll be happy you're going, it can be a lot of fun.