Hi Cynthia,
How great that you're planning your childrens first trip, staying at one of the monorail resorts will be a great experience for them, especially being so close to the Magic Kingdom. There are 3 resorts on the monorail, the
Grand Floridian, the
Polynesian and the
Contemporary. The Animal Kingdom Lodge isn't on the monorail it's close to the Animal Kingdom park.
Which you choose comes down to personal choice, they all have quite different themes but offer very similar facilities. I personally love the Grand Floridian, I love the classy feel of the resort and I can't wait to stay there at the end of the year. But lots of the other Moms on the panel adore the Polynesian, this has a hawaiian theme and is much more laid back than the GF. Then finally the Contemporary, this is very stylish and quite a retro hotel, it also boasts some of the best views of the Magic Kingdom from some of it's rooms. The monorail also goes right through the middle which your children might find pretty cool!
What I suggest you do is have a look at each resort on disneyworld.com (if you click the blue writing above it will take you to each resort) there you'll find lots of photos and some video and you can decide which resort you like the look of. If you then have any further questions please ask again.
Happy planning,
Jo