re: 3 Night Stay Recommendation - Flying into Cancun

Isla is more laid back and is my favorite place in Mexico.

Cancun you can get some great deals on hotels and AIs.
Look up Sandos is pretty cheap and is located in a walkable part of cancun.

You can get to Isla quickly if you hire a car service.
Carm is $100 both ways including ferry tickets $69 without. A cab will cost $80 each way.

I would get the carm car service. A ferry leaves every 30 minutes and the ride is 20 minutes. .
The longest part is the ride from the airport to the terminal.

Still I usually take the 12pm direct to Cancun from New Orleans and am walking around Isla Mujeres by 4 4:30.

I went there 5 times in last year..