I've used the second method (without 10K resistor) in my schematics and as much as it works I wonder why no pullup or pulldown resistor is used when RE pin2 is pulled high. The datasheets indicate this floats the RO pin1 and I wonder how a PIC UARTs RX pin is affected?
I could simply ground the RE pin as in the top MAX483 (and maybe that's the right way)
I'm sorry that I don't have anything to answer your question about the serial chips, but I must say, that is a very nice looking technical diagram ... call-outs with drop shadows, and a big blue star in the corner!