Don't skimp on shorts. The right shorts are important for long rides. Personally I like Shebeest Century shorts.
Lately I've been using Hoo Ha Ride Glide for chamois cream. Used to use Chamois Butt'r, which worked fine until I started being allergic to it. Others here like plain old shea butter.
You should carry a mini tool, frame pump, spare tube(s), a patch kit and tire levers on your bike.
You'll want to experiment with foods/beverages/gels etc. for eating and drinking on rides. My stomach usually can't tolerate real food while I'm riding, so I stick with Gu for "food."
You'll also want to be ready for whatever weather you'll be riding in -- windbreaker, rain jacket, arm and leg warmers, tights, whatever's appropriate for your climate (and the climate in Alaska in September).
Other things I carry in my bike bag: pocket pack of tissues, cell phone in a zip loc bag (in case of rain), albuterol (for asthma), chapstick with sunscreen, tiny bottle of hand sanitizer, various sizes of band-aids, jimi wallet with ID, insurance info, credit card and a little cash, Road ID on my wrist.
I use lots of Neutrogena Sport sunscreen SPF 70 and wear good sunglasses on every ride. I can change to lighter color lenses for low light conditions.
In addition to owning multiple pairs of shorts, I have extras of just about all my other clothing so I won't need to do laundry after every ride in order to have clean clothes for the next ride.
- Gray 2010 carbon WSD road bike, Rivet Independence saddle
- Red hardtail 26" aluminum mountain bike, Bontrager Evoke WSD saddle
- Royal blue 2018 aluminum gravel bike, Rivet Pearl saddle
Gone but not forgotten:
- Silver 2003 aluminum road bike
- Two awesome worn out Juliana saddles