This is one of the most amazing museums I have ever been too. First of all, it is kind of like up in the hills/mountain overlooking the city so you can take this little tram and you get a really amazing view of Los Angeles (although it would be more amazing if you didn't have the 405 at your feet sort of marring your view as you look at all the traffic). The museum itself is beautifully designed - the architecture is amazing and there is tons of glass and modern and unique and amazing features of the museum. You really feel like it is awe-inspiring when you first see it and you feel like you are stepping inside an architectural masterpiece.
Once you come inside you will not be disappointed in the selection of art that is available. There is a very wide selection of modern arts - you can enjoy Pollaks, Picassos, Warhols, everyone and everything you can imagine. You can also see more traditional art - there are many different wings of the museum and there is something to please every different art lover. There are also some fabulous sculptures and other things so everyone should be able to find something they find beautiful.
There is parking here and it doesn't cost a great deal. Admission is not expensive, especially for children under 12. In addition, on some Tuesdays admission to the museum is free to encourage people to come and check it out so if you are able to plan your trip for a Tuesday I recommend you check the Getty website to see if that particular day is a free day. I think it is the first Tuesday of every month but I could be wrong. Either way it is definitely worth the admission price - you could spend a whole afternoon there and not get bored or run out of things to look at. You can also have lunch at the cafe - it is really good food for a museum and they have a nice selection, especially rich on appetizers type foods and salads - I recommend the chicken Caesar or the bruschetta.
Overall, I highly recommend a visit to the Getty for the afternoon. Just beware of the potential for traffic, as the 405 is one of the more populated freeways of Los Angeles so if you go on a busy day it might take you a long time to get there. I rate this as one of my all time favorite museums in the United States and I am sure you will not be disappointed. They also have special traveling exhibits which give you an opportunity to experience even more art than they already have in the permanent collection.