Hi David
This tour is pretty full on but you will have some free time to go off and explore. I'm not sure if the itinerary has changed since I went but I remember that most of my group wished we had longer in San Francisco and less time in Palm Springs because there was much more to see in the former. Having said that, I recommend the Palm Springs ariel tram way (stand in the middle if you aren't good with heights....) but I wouldn't bother with the 'Living Desert' which is basically just a zoo.
Being a fan of maritime history, I loved the chance to go to visit the Queen Mary at Long Beach (we had a hotel right on the harbour but I think you are staying in LA itself). A tip if you go on board - don't take the audio tour because they demand your passport as security for the equipement! (And then leave them in a stack on the desk at the ticket booth - absolutely no security!) Sadly, the world's greatest milk shake place (I'm not kidding) - 'California Shakes' on board the ship closed down a couple of years back but QM is still a great place to see.
Santa Barbara is nice (but personally, I prefered Monterey) and Santa Monica pier is wacky. Tip - if your bus stops on Malibu beach for a comfort break - don't bother unless you are desparate - the stalls appeared to have been designed for the Lollipop Guild so when, er, seated comfortabley, the screen doesn't reach your shoulder so you have the bizarre opportunity to hold a face-to-face conversation with the complete stranger sitting next to you!!
Vegas is completely nuts - you'll love it. The 'Rat Pack' show is cheesey but great fun. The Stratosphere is great - I reckon 3 star for Vegas is 5 star anywhere else- and it's really easy to get the 'Deuce Bus' up and down the Strip when you are exploring alone (get a 24 hour hop on/off ticket - very good value) For the Grand Canyon, I know there are a number of tour options - most of my group did the '3 in 1' which we all thought was really good value and a great experience.
Finally - I know that not every bus stops there but ,when you pass through San Luis Obispo, if you get the chance to go to the Madonna Inn, take it. The place is madder than a box of frogs :-)
So there's a quick snap shot for you - let me know if you have any other questions, but have a great time!
Mandy