General

I was really disappointed in the food in Vegas, but I am pretty sure I just picked badly.

I would suggest AirBnB as at least something to look at. I was in Dallas in November and stayed in a 3 bed room house for cheaper than a hotel room for a wek.

Sorry for the wall of text!

If you took a flight out from LA to Minnesota, and then rented a car from there, there's quite a bit you could do. You could start off exploring the Mall of America and then make your way to South Dakota for all the tourist stops on the 90. The Corn Palace, Al's Oasis, and Wall Drug were some interesting places to check out. If you travel all the way to the end of the state, Mount Rushmore is just Southwest from Rapid City. Food wise I remember Pizza Ranch, Culver's, or even stopping by a Caseys General Store while on the go.

Since you're based in LA I would recommend the Coast Starlight train if you've never taken it before. It heads up to Seattle and the trip is beautiful as it goes along the beach, through cities, mountains, and also forests. Lots of leg room with reclining chairs. The meals were pretty average on the train, pricey burger and pizza options in the Observation car. The train goes to places like Portland Oregon where there's Voodoo Donuts to try out. Most of the areas up north are pretty fat friendly with cooler weather in the summer. If you take any Greyhound buses north from LA, during the off season you can usually get a seat to yourself pass Sacramento/Redding, but it's cramped otherwise and I only recommend it for the daring.

Seattle has a lot going for it even though it's starting to approach the rainy season. Pike Place market has the original Starbucks and lots of great food vendors. There are a lot of delicious Pho places like Than Brothers in the area too. The Space Needle and the Museum of Pop Culture are worth a visit. If you flew from LA to Seatac airport and got a hotel/car there in Tukwila; there's options to drive out to Tacoma to see the glass bridge, Point Defiance, and the Narrows Bridge. The Bavarian village of Leavenworth is a great place to visit in the summer, it's pretty much the Solvang of Washington. Lots of great restaurants there.

Driving the 101 up Cali has a lot of great stops too. Gardens of the World in Thousand Oaks, Harbor Village + Channel Islands visitor center in Ventura, all the shops and restaurants in Solvang. You could take it up to San Francisco, which is getting a bit trashy with all the drug use and homeless, but there's quite a bit there. Pier 39 is a great stop for lunch, along with Twin Peaks overlooking the city, Golden Gate Park and Golden Gate Bridge. If you make it all the way to Oregon on the 101, I recommend checking out Astoria and the nearby cities of Westport & Ocean Shores. Really great seafood restaurants in those areas.

Las Vegas I don't feel is very fat friendly unless you're just planning on staying at one hotel. It's a lot of walking just to look at all of the stuff on the strip, unless you constantly valet your car. Even with a monorail pass, there's just a lot of walking and heat to deal with. Outside of the strip, you mostly have the same restaurants you can find in SoCal. The Hoover Dam is the only thing I can think of in the area monument wise worth a visit. If you want a hell of an adventure driving in the middle of nowhere (except for break stops at Ely, Wells, and Jackpot), drive north on the 93 until you reach the Twin Falls bridge in Idaho.

Hahaha honestly I would say try and look up all the rest stops you can find along the way and star them on google maps for later. It's a lot easier to travel knowing when and where your next bathroom break is, or an opportunity to stretch your legs. Some rest stops have free pamphlets about stuff in the area or road maps of California. Same with gas stations, you can calculate your gas mileage ahead of time and estimate when you need to refuel. You can save money seeing which gas stations are cheaper online and aim to stop at those while on the trip!

If you want cheap souviners I recommend bringing quarters and pennies since there should be a bunch of pressed penny machines. Definitely bring a portable phone charger in case of a power outage or something happens where you can't recharge your phone from an outlet. That way you have a backup battery. I'd say consider too how you might bring back other souvenirs you might find? Im always one for grabbing free pamphlets or maps wherever I go, so I bring a folder with me to keep that stuff flat and undamaged haha.

For a San Francisco trip, you might need to decide if you want to follow the 1 along the coast after San Luis Obisbo, or continue on the 101 inland. Depends really how fast you want to get up there haha, I know Monterey on the 1 is worth a visit.