It is more expensive to live in Miami than in Orlando. I have lived in both Orlando FL and Miami Florida and trust me Miami Beach and the rest of the city are more expensive. Not to mention the crime rate is higher as I witnessed crimes there quite frequently.
Orlando FL has a lower cost of living based on food expenses, rent prices, property taxes, groceries and expenses brought on by weather and crime. By crime I mean your car insurance etc. There are cities that surround Miami and I have many friends that still live in the area around Miami and family too.
Miami is synonymous with high homeowner's insurance. It is at a greater risk than Orlando and is two wind zones higher on the overall risk chart. An often overlooked housing factor is the steady population growth by people moving to Miami because of the Latin culture and tropical climate. Other popular cities in South Florida or Central Florida have nowhere near the same growth. The household income is higher in Miami Beach but certainly not in most of the greater Miami Metropolitan area.
Obviously Miami Beach is gorgeous. However for access and enjoyment other cities if Florida actually have better beaches than even South Beach. Sure, visit Miami and get it out of your system, most likely you will not want to live there. I have daughters in law that are from South America and they don't want to raise their children there.
Walt Disney World, Universal Studios and many other theme parks draw 70 million visitors a year to Orlando FL. Our public transportation is better than the public transportation in Miami as well. We have art museums, affordable cost for housing and food expenses are lower as well. The choice is really clear, Miami is more expensive than Orlando.