Thank you both.
So, in that approach then a good max-size width for images would be 700-800px? Those seem about the width sizes that fit in the posting area.
And how does one calculate height for max-size? For example, I could have a 800x600 max in the ACP but then I may have a 'long' image that's around 800x1000 height. Or is the height automatic and adjusts itself to whatever the width would accord?