Well if you stay onsite at the DLH, Paradise Pier or the Grand Californian, there is the monorail there that will take you directly to the park. Although the Grand has an entrance in the hotel that goes directly into the DCA park. So thats kind of handy. But all have the monorail going to the main entrance.
But if you want something cheaper and closer, there are TONS of great surrounding off site hotels that are even closer then the big Disney hotels. There is the Carousel inn, Ramada main gate, Howard Johnson, Candy Cane inn etc. Those are off site but are walking distance. Some are directly across from the main entrance and no transportation is required.
If you are staying a few blocks away from DL, there is ART which is a bus system that is pretty much dedicated to
Disneyland. It picks you up at your hotel to take you to Disneyland, and then will dropp you back off at your hotel. It runs about every 20 minutes. It is really handy and extremely easy to use. It runs until one hour after the park closes, so although its handy, it makes you limited to what you can do. There are taxi's EVERYWHERE in the bus loop area, so you can always catch a taxi back to your hotel.
If you want to get a car to drive to farther attractions such as Universal, Sea World, Sandiego Zoo then there are great car rental places such as Alamo. But if you dont get a car, then from the airport (If you are flying in of course) there is "Super Shuttle". If you fly into SNA Supershuttle is only $10 per person each way and will take you directly from the airport to your hotel. You can even make reservations for them to pick you up from your hotel on your last day and take you back to the air port. Its a cheaper way to go and its so convenient.