I will be going from Provence to Barcelona and flying home from Madrid in May. I really want to go to Granada for 1 day with possible overnight. I know flights have been very cheap recently. Do you suggest planes, trains or combinations? Should I go Barcelona-Granada-Madrid or from Madrid-Gran-Madrid? I like overnight trains, because it saves the extra cost of a hotel room.
Granada is WONDERFUL.
Since it is quite close to Madrid, I think taking a train from Madrid is the most efficient route. Or a bus. It is only about 3 hours and you would probably spend much longer than that in the airports (with arriving early and then having to wait for your bags).
You can't do Granada in a day...the distances are too long. From Barcelona, you can pick up a cheap air fare from clickair.com for as low as 25 Euro in May (fly Mon-Thurs if you can). The 6:45 flight from Barcelona will have you in Granada by 8:15. Or you can do the overnight train, but that can be expensive. From Granada to Madrid is about 450 kilometers....about 5 1/2 hours on the bus, about as fast as the train, and far cheaper (they stop about halfway along the route for a rest....probably no washrooms on the bus.) You'll see some magnificent scenery as you cross the mountains to the high plains of La Mancha, with dozens of the famous old windmills in sight!
You really should stay overnight in Granada. Granada is not as close as you think from Madrid. Also, Granada is wonderful and you want to enjoy it rather than rush back to Madrid.