One of my favorite little tools is opening 1D only with unbalanced hands and therefore including in 1C any balanced hands even if diamonds are (much) longer. One of the benefits is very subtle.
Consider two hands from yesterday's Swiss Teams.
On one, my wife opened 1C, dutifully alerted. RHO held both majors with clubs (4-4-1-4 type) and decided that a double in this context should show both majors and ONE of the minors. I tend to agree.
However, at favorable colors, I had seen this situation before and opted for the "odd" call of 1NT with 2-4-5-2 shape and two queens. I immediately removed the two-level from their discussion. LHO tried 2D, passed out. They made, but 2S would have made 140. The extra level convinced RHO to not risk further problems.
Later, partner again opened 1C. This time, RHO made a normal 1S overcall, and I doubled for hearts. LHO passed, and partner bid 1NT. Not knowing whether my wife had diamonds or clubs dominant, RHO felt almost forced into a 2C call, lest they be blown out of their possible club fit. As it was, partner had the normal club-spade two-suiter (2425) and the opponents ended up -200.
In either auction, the opponents might have resolved the problems better. However, adding an ever-so-slight problem for them, and knowing how and when to induce failure in these types of sequences, is the kind of subtlety that I love. Our teammates were impressed by the 6C contract we reached that the opponents missed, for a huge gain. But, I enjoyed, even more, the couple of small gainers we got from these more subtle actions.
That said, flamboyance is also fun. We had another where LHO opened 1S and partner overcalled 1NT as a light takeout (less than an opener down to, whatever). RHO decided to double and sit back. With xxx-Axxxxx-void-xxxx, it seemed like RHO was opting a double with spade support, which is odd. The only explanation, it seemed, was that he was thinking slam. So, wanting a diamond lead against 6S, I bid 2D. This was passed to RHO who, with KQ10xx in diamonds, could not stand it and doubled. I showed my "second suit" by bidding 2H, and LHO doubled. Pass, long hesitation... ("Please go for the BIG number -- we are in TROUBLE!!!") Well, the vibes did not work when RHO ended up bidding 3H. After a few bizarre bids, they ended up in 4S, a huge gain when 6S is cold (RHO was void in hearts). As added insult, our teamates made the overtrick in 6S, while we held 4S to 12 tricks (partner grabbed the induced diamond).
But, I still like the subtle ones best. The pro usually can deal with wild lunacy, but even the best fall prey at times to the very slight nudge. Actually, the pro is more likely to get snared by the nudge than the average player.