Disney

Disneyland is only one park and it should be avoided. However, should you for some perverse reason decide to shell out ridiculous yen for the fun of waiting in lines for hours, afterwards you shouldn't stay in Chiba.

There are two separate parks: the original Tokyo Disneyland and Disney Sea, the latter, as the name implies, has more water-based rides. It's up to you, but many fans think the Disneyland still has an edge on thrill rides.
Accommodation at the park is very expensive, and those nearby aren't much cheaper either. You should stay in Tokyo and just take a train to and from Disney: JR Tokyo to Maihama (nearest station) on JR Keiyo Line, only takes 18 min and costs 210 yen. No need to stay in Chiba, which offers little for tourists.

There are less expensive accomodations (but still not budget level) at the Keihin Makuhari station, which is even closer to the Tokyo Disney parks, probably only 5-10 minutes on the JR Keiyo line. Plus there is a Costco there if you are a member and happen to need a package of 50 bagels or 35 rolls of toilet paper.

Tokyo Disneyland is similar to the ones in the US, Europe and HK, but Disney Sea is the only one in the world. But crowds in Tokyo are longer. Avoid weekends and public holidays.

If you want to enjoy a day full of magic and fairytales, then you should go. Its different from Disney in USA, people are very spontaneous, 1st thing they do upon entering the park is to purchase either Mickey / Lilo / Chip & Dale hat. The popcorns are of diff flavours in diff containers which can be kept for souveniors. Its really special and there are diff themes in diff seasons. Try going on a weekday instead of weekend, less crowd and shorter Q time.