If you raise you take control of the hand, and from late position that's something you want. If you raise and get 3 callers, and you're in position on all three, and they all check to you, it's possible they've all missed, and a continuation bet will take down a smallish pot. If you flat-call, and the same three players are in the hand, how are you gonna bet anybody out, or even bet for value if you hit?
Flop comes 955. gg. Flopped the nuts and guaranteed no action short of somebody flopping a boat, or catching a pair on the turn/river.
I know, I know. I KNOW!! How many times is the flop going to come 955? More like AJ5, right? Because we always get the flops we want?
If you make it 3 BBs with 55, and the flop comes ugly, or the flop comes with a 5, there's 12 BBs in the pot worth playing for. And I, for one, hate playing for pots with nothing in them.
Perhaps a stronger player than me would tell me that's a leak in my game. I'll let you know I've flopped a lot of sets in unraised flops (somewhere around 12% of them), and more times than not I'll end up raking a pot worth well over 8x what it costs to call.
I read once a set is a stacking opportunity, and I agree. It's a hidden hand you're not going to get credit for if you play it correctly. You're going to have a hard time stacking off a hand on a flop with 4 BBs in it, unless your opponents have like . . . 6 BBs each. If that's the case, what are you doing playing at the table?
Oh yea. All these strategies apply to cash games. But I'd play the tournament hands the same way, based on the table. (If their flat calls tend to be honest rather than deceptive - If I've been getting call/raised a bunch from crafty players, I would call with any of the hands in question, otherwise I want something in the middle to play for other than a few BBs, except in late stages of a MTT, where 55 and I'm SS? If I'm playing it'll be for all my chips.
None of those hands are reraising hands, though.