To slow play or not to slow play

How often does this situation come up? A paired board with an undercard, such as this:

9-C, 9-S, 2-C

In the above situation, when I have a nine, I used to think it would be profitable to check and slow play a bit. What I've found, though, is that someone with a two will often call, and an opponent with any two cards above the two might also call on a draw, so betting is usually better. And since flushes or straights almost always seem to be a possibility, whether immediately on the turn or in the backdoor, I like to make people pay to play. But what about the situation where you have the following:

2-H, 2-D

with the above board? I think then you need to really, really determine if your opponent has three of a kind, as you can probably get them to stick all their chips in most of the time. Well, such a situation happened to me the other night in a $1-$2, $60-$200 game at Harrah's in Kansas City. I was on the button, and I raised it up with a pair of deuces after the action had folded around to me. Both blinds called. One was a female who played fairly aggressively, but seemed to bet big postflop, because she either wanted to protect a big hand or because she overvalued a hand. The other guy loved to try to overbet in order to make tighter players fold, and since we had no history, he felt that I fell into that category. Well, the board came a pair of nines and a deuce. Plus, I was last to act. Currently, there was $18 in the pot. The aggressive girl bet out $8. The big blind called. I felt like the girl *might* have a nine, and so I raised it up to $35, which is a fairly large raise, but I knew we could get my $280 into the pot quicker if she did. She called. I figured there was little possibility that she had a J-2, so I was ready to push. There weren't any scare cards for me, but I wouldn't have minded if the flush card came, as I was already boated. In fact, if she was on a draw, it could do nothing but good things for me. The big blind folded. On the turn, with $88 in the pot, she bet out $45. I was certain she had a nine, and I just hoped she wouldn't hit her kicker for a better full house. I definitely wasn't going anywhere, so I went all in there. She immediately called. Huge pot. Sure enough, she had a:

J-H, 9-D

and neither a nine nor a jack came, so I doubled up. If I get the sense that my opponent doesn't have a big hand when I flop something like this, I might be included to bet small or even check. Poker is such a game of feel.