I tend to look at the % seeing the flop as an indicator of how loose the table is, which is my main priority (in Omaha High/Low, anyway). Then the pot size gives some idea, but I'll often watch a table for a couple of hands to make sure that it's fairly passive before sitting down. This can additionally be helpful, because you'll want to know how the table responds when there is a bet pre-flop, so you know whether it's worth betting to swell the pot or whether you'll have more success betting to thin the field.
One thing that does really show you the advantage that position can give you is on some of the freerolls
. Some of the Jungle Poker freerolls had 6-8 sit-outs at a table at some points, and Party sometimes has a lot of sit-outs. Not only do you effectively play short-handed, but when all the sit-outs are after one player, then they effectively get position over the other active players much more often, and you clearly see how this lets them steal more pots and generally outplay their opponent. Generally in those kinds of freerolls, the other players have to put all their chips on the line to get much profit against an aggressive position-holder, while the one with added position from the sit-outs steals a lot of pots, and can afford the occasional gamble to knock out the other players. One sit-out after you, preferably 2, will give you a significant advantage, and it will teach you more about playing position.