Areas for discussion.

I didn't wantSerial.println("x", x, "y", y, "z", z);
I'd like improvements of the serial monitor to provide:
a. clear screen/window,
b. position the text cursor to a specific row and column for subsequent print (maybe position within current row)
c. clear current row
d. return text cursor to start of line with '\r' (rather than forcing a newline)

I don't mind how it is achieved. mem would prefer it not to consume precious Arduino team time, and suggest that it could be an existing Open Source terminal.

On the Arduino side, I would expect these capabilities to be nicely wrapped up as methods in the Serial class to make it easy to use. The same capability may be exposed as 'magic' characters which could be embedded in character strings and Serial.print()'ed.

mem and I would like it to be easier to create tabular output.

I would be satisfied with something that returns the character length of each type of printed item, e.g. if Serial.print(int) prints on the serial monitor, then Serial.length(int) would return the number of characters that would be printed. Then I'd like something to make it easy to pad with spaces, e.g. Serial.pad(int) would print 0 or more spaces. That would be enough for me to do tabular layouts.

I hope this is clearer, and that I haven't misinterpreted mem.
GB-)