I have been travelling to California / LA area every year for the last 8 years.
I am a solo travellor and I dont drive. I have friends who live in California and I either make my way around on public transport or my friends drive.
My trips are usally around 10 days and are 2 locations.
For
Disneyland I stay in Anaheim, 3 times at Motel 6 Main Gate and this June 2017 at Dessert Inn and Suites.
I have stayed at
Comfort Inn in Santa Monica
Hotel Kwada and The Milner Hotel in Downtown LA
AirBnB in South Pasadena
One year I met my friends in LA and we drove to Vegas stayed at Mandalay Bay hotel and drove back to LA. I have also been to Vegas with my mum and sister and we stayed at The Bellagio.
One year I did a short 2 day trip to San Franciso to visit family
Places / things I would recommend
Stay in LA / Burbank / Hollywood / Universal City for Universal Studios
Stay in Anaheim for Disneyland
Stay in Santa Monica / LA / Hollywood for the main tourist sites
Hop on Hop Off Red Bus Tour
Warner Bros Studio Tour
Santa Monica for beach / shopping / restaurants general really nice area to stay
Drive up the Pacific Coast Highway to Santa Barbara
Santa Barbara county in general for mountains, winery's, really nice Dutch area of Solvang
The drive to Vegas from LA takes alot longer than it seems. Maps / GPS will say 4 hours but it took about 6 hours. That motorway is a major commuter belt and the traffic can get crazy. Also you need to stop either in or before Baristow to refuel as thats the last civilisation before Vegas.
I usually book flights and accommodation in January for travel in June.
I would definatly advise having everything booked and planned out. Hotel prices have really escalated in the last 2 years so I would never just hope for the best and find somewhere on the fly.
For Vegas, the hotels on The Strip are like separate resorts. Yes you can get tickets to shows on the day but some shows may be fully booked or may only have restricted view tickets left. Again book in advance. There are alot of Grand Canyon tours availbe in Vegas. My mum and sister did a helicopter tour sunrise tour of The Grand Canyon, they were picked up and brought back to our hotel.
My advice is to divide each place into a section and list out the Must Do's and the Would Like To Do.
Then plan out each one day by day. Know that you will have to book hotels and attraction / show tickets in advance.
California and LA are huuuuge and theres no way you will fit in everything. After 8 visits I have really still only seen or been to the highlights