I (Don) am riding a 10 YO Surley Long Haul Trucker. This bike is absolutely terrific. It's made for long distance touring. It's durable, comfortable. And made of steel so it's bulletproof and heavy as all get out (34 lbs unloaded). I bought it used about 5 years ago and have only changed tires, chains, pedals & saddle. I rode this loaded across the USA 3 years ago and it performed flawlessly.
Just before my 2019 ride I installed 700x35 size Schwalbe Marathon Plus tires with tire liners and slime tubes. Whether because of that set up or sheer luck I had no flats or leaks during the ride. In fact, I just changed these last week after putting a little more than 8,000 miles on them over the last 3+ years with no leaks or flats. Remarkable. I replaced them with the same tires, liners and tubes but this time with 700x38 size. This translates into about a 1.5 inch diameter tire which is more comfortable and durable especially on rough roads. I put the same tires/liners/tubes on Liz's bike. , so we'll be well served by slightly larger tires.
My bike has 3 water bottles and 2 nylon bags to hold various bits we need during the day like jackets, tubes, tools, wallet, camera, phone etc.
Liz will be riding an 8 YO Specialized Sirrus that I also bought used. (Sensing a pattern here? Think I'm frugal? Oh yeah.) This bike has an aluminum frame with carbon forks and is extremely comfortable and stable to ride and only weighs 26 lbs. I changed the saddle, pedals, handlebar and tires. Her bike has 2 bottles and 2 nylon bags.
And finally I will bring my old Cannondale R800 aluminum bike as an emergency back up unit, in case something goes totally haywire with one of our main bikes if we're hundreds of miles from a bike shop.
Finally we'll have a load of spare parts, tires, tubes and tools in the RV in case I have to fix something. We will be pretty self sufficient out there.