I recommend riding on Interstates when necessary. People have this preconceived notion that it's dangerous for cyclists. I found the opposite to be true. The shoulders are huge and traffic can see you long before they pass you. The scenery gets dull, but it's still there if you know where to look.

Most interstates allow you to bike on them once you're outside of city limits. There will also be signs saying all bicycles must exit now as you approach a new city.

Be very careful when using I-10 through AZ, NM, and CA. It can be 20-40 miles in between food. Thankfully there are rest stops where you can get water usually every 10-20 miles. Still, it gets very hot out there and you need to take precautions. When I used 10 to get from Phoenix to CA, I would find a place to rest around 2-4 to wait out the hottest times of the day.

I stopped under an overpass for shade once and someone called the cops on me thinking I was dying of dehydration. Another couple stopped to make sure I was ok as well. It's serious heat out there.

Besides that, interstates are good in my book. I-40 through New Mexico was some of my favorite riding on my tour.