The only problem with
Heinlein is that as he aged, he became a
dirty old man. Virtually all of Heinlein's later books are of the dirty old man category.
I grew up with Heinlein. My first experience was with Waldo and Magic, Inc., when I was far too young to understand what was going on. After recovering from that experience, (I'm sorry, but 2nd grade was far too early for that book.) I moved on to some of Heinlein's earlier works like Have Spacesuit, Will Travel, Starship Troopers and The Number of the Beast, fantastic books for a young developing mind.
By the time I read any of his dirty old man books, I was in the throes of a very confused adolescence, probably explaining why I did not mind the prejudices at the time. Recently, I have re-read some of these and I found that they were no longer as satisfying as they were in days of yore. I often found his sexism to be offensive. It seems interesting to note that his masterpiece of the open mind, Stranger in a Strange Land, seems to mark the beginning of the closing of his mind towards women.
Heinlein's career and books seem to reflect the most common path of intellectual growth in our society. In youth, we are playful, open, and curious. As young adults, we are idealistic and interested in righting all the wrongs of history. Towards middle age, we begin to consider experience increasingly important. We start to discount the experience of others in favor of our own. Finally, our minds, rendered inelastic by age and disuse, become closed to new thoughts and begin repeating old arguments incessantly. I am sad to note that in what should be our golden years we are often instead angry, tired, and bitter.
Please make sure you have read a full spectrum of Heinlein's work before you make judgments on his career. Too often, our attention span is short and we only consider the most recent. Please, do not let this happen to you.