I want to give you some specific information from the Unofficial Guide (typos will be mine):
"In-Room baby-sitting. Three companies provide in-room sitting in Walt Disney Word ... They are Kid's Nite Out (a Kinder-Care company), All About Kids, and the Fairy Gomothers...Kid's Nite Out also serves hotels in the greater Orlando area, including downtown. All three provide sitters older than age 18 who are insured, bonded, and trained in CPR. Some sitters have advanced medical/first-aid trianing and/or education credentials. All sitters are screened, reference-checked, and police-checked...Many sitters arrive loaded with reading books, coloring books, and games. All three services offer bilingual sitters."
"Childcare centers. ...Services vary, but children generally can be left between 4:30 pm and midnight. Milk and cookies, and blankets and pillows are provided at all centers, and dinner is provided at most. Play is supervised but not organized, and toys, videos, and games are plentiful...Alll clubs accept reservations with credit card guarantee. Call the club directly ro reserve through Disney central reservations at (407) WDW-DINE. Most clubs require a 24-hour cancellation notice and levy a hefty penalty of $15 per child for no-shows. If you're staying in a Disney resort that doesn't offer a childcare club and you don't have a car, you're better off using in-room baby-sitting. Trying to take your child to a club in another hotel via Disney bus requires a 50-90 minute trip each way. By the time you have deposited your little one, it will almost be time to pick him up again. Child care clubs close at or before midnight. If you intend to stay out late, in-room baby-sitting is your best bet"
Here is the important information from above on in-room sitting: All three provide sitters older than age 18 who are insured, bonded, and trained in CPR. Some sitters have advanced medical/first-aid trianing and/or education credentials. All sitters are screened, reference-checked, and police-checked
And on kid clubs: If you're staying in a Disney resort that doesn't offer a childcare club and you don't have a car, you're better off using in-room baby-sitting. Trying to take your child to a club in another hotel via Disney bus requires a 50-90 minute trip each way. And Child care clubs close at or before midnight. If you intend to stay out late, in-room baby-sitting is your best bet
These things can make a HUGE difference on what your SIL would be more comfortable with and if you have the time to even use the kid club.
Other important information (rates not included b/c my info. is outdated):
Kid's Nite Out, 407.827.5444, kidsniteout.com, sitters are male & female, min. charge is 4 hours, cancellation deadline is 24 hours prior to service when reservation is made, forms of payment are visa, MC, AMEX, Discover, gratuity in cash, Sitter won't transport children in private vehicle, take children swimming, give baths.
All About Kids, 407.812.9300, all-about-kids.com, male & female sitters, min charge is 4 hours, cancellation deadline is 3 hors prior to service, form of payment is credit card to hold reservation, sitter won't transport children or give baths.
Fairy Godmothers, 407.277.3724, sitters are mothers and grandmothers, min charge is 4 hours, cancellation deadline is 3 hours prior to service, for of payment cash or traverlrs checks cor actual payment, gratuity in cash, sitters will not transport children, give baths. Swimming is at sitter's discretion.