re: Poker & FL $1/2.00 AK, sb. What would u guys have done???
Hmmm... the only hand you lose to here is 66, although it does really look like he has it... Still, maybe a less-than-solid player would do this with a worse 2-pair or has "slowplayed" AT or something like that and doesn't believe you'd check the flop with an Ace. Or he could have slowplayed 99.
Seeing as no worse hand will bet if you check the river, and any better hand (i.e. a set) will surely bet if you check, you have to spend at least 1 bet on the river, so don't think of it as "I'm losing 2 bets if I bet and get raised". You're losing just 1 extra bet when he has a set but gaining 1 when he doesn't... so you have to weigh up whether you think it's 50%+ that he has a set.
Since the only set he has here realistically is 66, I'd say other hands like 96 suited, A6 or K6 are statistically just as likely, making it worth a bet/call. This is where you check your HUD and see how many hands he's playing - would he limp in with something like that? If he's a solid, tight player, (VPIP<20%) 66 is more likely and you should check/call.
He'd have to be a donk to be capping the turn with a flush draw - however that's a situation where the check-call might get an extra bet.