There are several types of VIPs who can appear in your elevator at random. These special guests give you bonuses that can boost your coins or make things happen more quickly.
VIPs might randomly appear in your lobby if there is room. You can tap the lobby, then the VIP, to put him or her into your elevator. Then you can deliver that VIP to the floor of your choice. If you are not sure where to send the VIP, you can send him or her back to the lobby, but first you have to send that VIP to a floor and say "no" when asked if you want to deliver him or her there.
The construction VIP wears a yellow hard hat and an orange jump suit. If you send a construction VIP to a floor that is under construction, the construction VIP will reduce the construction time by three hours.
Big Spender VIP
The Big Spender wears sunglasses and a green outfit. If you send the big spender to a floor that has items in stock, the big spender will choose a random item and buy all of what's left in stock of that item. You can get a huge amount of coins this way if you have a large number of expensive items in stock, but if you choose poorly, the big spender might buy a cheap item that only has a small number left in stock. It helps if you can remember which of your stores have the largest amount of stock and have been stocked most recently.
The celebrity VIP wears a pink outfit and sunglasses. The celebrity can change a bitizen's dream job to match the floor where the bitizen works. This is especially helpful if the bitizen has a 9 stat for the type of business where he or she works. Always send the celebrity to a business floor, and always to a floor where at least one of the hired bitizens isn't working at his or her dream job.
The delivery VIP wears a dark brown jump suit. Send the delivery VIP to a floor that is not fully stocked and has at least one employee. The delivery VIP will fully stock the floor.
Real Estate VIP
The real estate VIP wears a dark blue outfit. If you send the real estate VIP to an apartment that has fewer than five residents, the real estate VIP will fill that apartment with new bitizens so that it has five residents.