I think I should be able to help out some since I’ve been all over the US a number of times, and once through Europe. I’m on the other side of the US so I can’t really help you with what’s out there, though I do remember taking US 395 from the start in the LA area all the way through Reno and it was nice.
I’m going to give you tips on what to wear, how to travel things like that.
As said before backpacks are not the best thing in the world. I don’t remember what kind of bike you have, but you can get saddle bags that basically get thrown over the second seat, make sure you check to see if you’ll need braces or not. You could also get permanent bags as well. If you have a sissybar you can get a bag that attaches to that, I had one of those for my old Shadow, worked nice. Or the old stand by of bungee cords or nets will work.
You do not need as much as you think, I tend to take a pair of undies and socks for each day plus one, a couple of t-shirts, and an extra pair of pants. So for a week I would pack seven pairs of socks and underwear, plus the ones I’m wearing. Maybe three shirts and if you’re not wearing a riding suit an extra pair of jeans. I would also carry at least one other pair of gloves for when it rains.
I’d also think about wearing earplugs. It sounds odd, but you will hear more because the wind noise is cut down, and it reduces fatigue after a few hours in the saddle. I almost always ride with ear plugs, even for the 20-30 minute ride to work.
Get some sort of cammelback or other way to drink water. You need to keep drinking water all day long, having it right there makes it easy to drink.
Along with the cammelback get a tankbag if you don’t already have one. A map case would be a nice addition on the bag as well. This way you can keep snacks and extra gloves right there.
As for finding a place to stay, unless you want to pay big bucks, stay away from big national parks during the summer, nice to see, but not nice to pay. This doesn’t apply to all parks, the Bad Lands and places like that I’ve stayed at over the 4th of July for $40 a night. But in California you might have problems at least in cost. I can’t remember a time that I was unable to find a place to stay even if it was expensive.
The big thing now is distances. I don’t know how far you’ve traveled on your bike so it makes it hard to say. However, unless you’re only planning on going a couple of hundred miles one way to make sure you have an idea of how far you can go. You probably don’t want to do the Bad Lands if you haven’t traveled 500 miles a day before because Google says it’s 1400 miles one way so over 7 days you’re talking almost 500 miles a day. That’s not going to be easy unless you’re used to it. Typically the furthest you can go would be on day one and the distance grows shorter from there. I tend to find one place that I want to see as my furthest out point. If I make it there early then good and I can change how I want to come back. This is where you need to know how much you can do in how long.
You could also do a motorcycle tour like I’m putting on. Basically you have a flag and a list of places to go, and you take a picture of your bike and flag at a city limit sign. This makes you look for places you’ve never even heard of before and can be an adventure.
If you have any other specific questions let me know and I’ll try to answer them. As I said before I did a lot of traveling when I was in my late 20s and early 30s by bike. I’d like to get back to it, but with one little one and another on the way it’s very hard.