yes i take into consideration like everything you named when i buy a pipe. i'm picky too....
bowl size - no bigger around then a penny becasue that's enough of a bowl to be more than a 1 or 2 hitter but it doesn't take a gram or so to pack a bowl, good for those last stash bowls
hole sizes - the mouth peice hole i prefer to be smaller than the hole at the bottom of the bowl as that allows thicker smoke to build up inside the pipe, thus, imo giving better hits
carb hole - as big as possible while not being ridiculous big...if i could i'd get one with width of a bic pen as it'd allow more air in, thus giving you a quicker 'shot' of smoke.
depth - should be longer then the bowl is wide, as skinner, deeper bowls burn less material then wider, shallow bowls, but at the same time should be no more than 1.5 times the length of the width of the bowl.
thicknes of glass/metal - simple the thicker the glass/metal the less likely heat is to travel to the mouth peice
screen - unless smoking shake (atleast out of a pipe, always use a screen on a bong) i do not use a screen....i prefer to have tid bits of good weed fall down in my pipe to be resonated to be scraped later on for further consumption
big to little pipes - 3 or less people little pipes, as there's no reason to break out some huge bowl'd fucker for 3 people when it just 'wastefully' burns weed (more cherry more burn between passes and holds of hits) any higher and it's time to break out the big guns, as by the time it comes back to you, you'll have already blown out your hits eliminating useless relighting and is just easier then having to relaod after every round or two.