I-10 is fine except for Louisiana, but there are only bad roads in Louisiana. Be sure to take the I-12 bypass around New Orleans.
Then get on I-75 off I-10 to Disney. Take the Florida Turnpike to Orlando off I-75. You can take the turnpike to Miami from there. Be warned that south Florida traffic is very very bad. It took us an hour to go less than a mile on US-1 in Miami. And I got off I-95 to look for a neighborhood in Miami drove a couple of blocks in the traffic and then fought my way back to I-95 and gave up on the visit.
Take the Turnpike south from Miami until it ends in Florida City head straight south to US-I to the Keys.