I checked out the FAQ on several rental car web sites. Most of them had clearly defined policies on extra drivers. Here's a summary:
Alamo doesn't charge for spouse if you're a member of their Alamo Insiders program, which is free to join.
Spouse is free with Budget.
Spouse is free with
Avis.
Hertz is free only if booked with an
AAA or AARP rate, and both drivers are members of that club.
Dollar charges for spouses.
Spouce is free with National if primary renter is a member of their Emerald Club, which is free to join.
Thrifty web site says they charge for spouses "at most locations." Don't know specifically about Orlando.
Enterprise charges for spouses.