MyTravel flights are good so long as you get a Mytravel plane. Seat back TVs, decent seat pitch in economy, well organised travel. We've gone with them twice from manchester and it's been fine.
The problems start if you go from a smaller airport and they sub-charter from Monarch. Tight seat pitch and central TVs. Monarch planes that we've gone on from Newcastle have all been dropping to bits.
A good tip is to do the Idrive check in for your return journey. They have a small office on Universal Boulevard just before Wet and Wild. You can check in there and drop your baggage for $10 pp then go and have your dinner at leisure and not rush about getting to the airport.
Sanford is there for British tourists. All car hire places are within walking distance, ie over the road from the terminal, and have enough staff on so there's never been a wait of more than a few minutes for us.