Rent an inflatable slide for children's group activity
If you plan on having many children of varying age, you may want to consider renting more than one inflatable slide. With the wide variety of designs they are available in, you will have plenty of choices. Encourage the smaller children to play on one toy and the larger children on the other. They can take turns at each toy to prevent boredom, but by separating the children by size you reduce the risk of the smaller children being hurt if a larger child jumps or falls on them.
Another consideration before renting an inflatable slide is what kinds of accommodations you must provide for the toys. You will need to be close enough to electrical outlets that the toys can easily be connected to power. They need to be connected the entire time they are in use, as a blower is necessary to keep them inflated. If the area where you are planning a party is not close to electricity, ask if the party company will provide generators.
Finally, ask the party supply company how many staff members they plan to send, and how many you must provide. Some companies will provide enough people to set up and supervise the toys the entire rental period. Others will provide crew for set up and tear down, but you must provide your own crew to supervise, or pay the rental company an extra fee.