Full Duplex RS485 recommendations
I'm using the ADM2582 because it is an isolating type, has the voltage generator inside and can be run 2 wire or 4 wire: -



If anyone says that these are expensive (+£5 each) I say I don't give a damn because performance comes first on some parts of any job!

Also I'd like to point out that many folk do use full duplex RS485 because it's far easier conceptually to build repeaters on long line lengths. You can use two chips like the above (or non-isolating type) and wire them back to back. You can always convert to 2 wire at one end should that be necessary.