Three Vegas hands stand out in my memory.  First a play problem.

IMPs (KO)

You have 8 tricks in in 3NT and must play this suit (spades).

ATx

xx

Lefty overcalled in this suit at the 1 level and you've already lost a trick to the Queen.  You play low towards the ATx and Lefty ducks.  Do you finesse for the overtrick? (If the finesse loses you are likely down.)

Additional information: 3NT was a hopeless contract but RHO was defending 2 Spades on the hand (the suit her partner overcalled in) and tried to give her partner a 'ruff'.

Same match:

AK3 / x / xxx / Qxxxxx

JT9xx2 / xxx / KJ / AK

RHO opened 1NT and you bid 2 Clubs (Capp, showing a single-suiter, alerted by partner) Lefty doubled (Stayman) and partner bid 3 Clubs (don't ask me why, if my suit is Hearts (likely) we're too high already.  If it's Spades then we belong in game.)  I bid 3 Spades and partner raised to 4.

Jack of Clubs lead.  Plan the play.

xx / Ax / Axxxx / Axxx

You opened 1 Diamond.  LHO overcalled 1 Spade.  Partner doubled.  RHO bid 4 Spades.  Float.  Partner led a Diamond.  Declarer calls for the King.

KTxxxx / Qxx / Kx / x2 Dummy (RHO)

xx / A2 / Axxxx / Axx3

Plan the defense.

If you cashed the Ace of Clubs and then the Ace of Hearts (probably not best) partner played the 4 of Clubs and then the 3 of Hearts.  (playing upside down carding)  Now what?

On the first hand, my partner actually finessed and went down.  I was in shock.  We'd had a pretty rough set (this board was towards the end of the first half) without doing anything particularly awful.  It was apparent from the tabletalk that one of our opponents had lost her mind and that we were slated to pick up at least a half dozen and maybe a lot more here.  Instead of tied we were down 12 at the half.  Same partner passed my 1 Diamond opener with an Ace and a King.  Some folks might enjoy that style of play, but to me it's not bridge.

ON the second hand, same match, I was declarer.  The opening lead screamed singleton to me.  Even if it's not, I'm allowed to be lucky ONE TIME and have trumps break 2-2.  I won the Club and led the Jack of Spades.  About 5 seconds later LHO managed to play a Spade.  ... Whatever ... I called for the AK of Spades.  LHO showed out on the 2nd one.  Down in a cooler (both Diamonds onside.)  Had to play to ruff 2 Hearts in Dummy.  LHO had led the Club from Jx even with a singleton trump.

The final hand was from the last Sunday.  I had played essentially perfect bridge all day and here partner had to decide if he was in the bridge-playing business or the partner-****ing business.  Do you continue a Club or a Heart?

For starters, I hate partner's defense so far.  Normal defense to me is to win the diamond and cash the Ace of Hearts.  If partner encourages (from known length) then cash the Ace of Clubs (just in case Declarer is 5-2-4-2) and continue Hearts.  If partner discourages, then underlead the club Ace.  If partner plays the Jack of Hearts (and isn't the type to throw an honor as a 'normal' discouraging signal) then give him a Diamond ruff (Declarer could be 5-2-5-1.)

But once you choose to follow this path, the hand to me is awfully simple.  You can choose to trust the Club signal from unknown length, you can choose to trust the Heart signal from known length, or you can flip a coin.  Obviously the Heart signal is more reliable.  Partner might have Qx in Clubs and was reluctant to part with the Queen.  He signalled encouragement in Hearts AFTER the Club play (with consequently more information) and from KNOWN length.  Continue hearts.

This was the one hand I slipped on during the 2nd Sunday Swiss.  I held:

x / KJTxxx / Txx / QJx

When partner switched to the Ace of Clubs I should have played the Queen.  But I was under the gun and it seems normal for partner to have already switched to the Heart Ace if he had it.  I also didn't want to break tempo and make a decision because that puts a lot of ethical pressure on partner.  So I played low in tempo. 

In spite of my unambiguous encouragement in Hearts from known length (from my negative double) partner switched back to Clubs and Dummy's heart losers eventually went away on minor suit winners.

KTxxxx / Qxx / Kx / xx

AQJx / xx / QJx / KTxx