first off... HAPPY BIRTHDAY WII!
2 great experiences, first when i got the wii. my bros got it for me, and we played it all night... and most of the morning. even my mum had a go. it kicked ass, and we played again at lunch time.
2nd was a partyish thing... we didnt do alot of partying, but half way through a party, 10 of us left and went to my mates house down the street. i had my wii there, and his aswell, plus 3 DSs and two psps. it was AWESOME. video game fest, mario kart was awesome on ds, so was tekken on psp. but the wii was what everyone REALLY wanted to play (and seeing as we had one set up on a huge projector and the other on a plasma, it rocked). wii sports+gh+mario strikers+rayman+some vc titles (mostly streetfighter and mario kart)... THAT NIGHT ROCKED!
there have been plenty more wii moments where friends came over... but we were on the grog that night, so it takes the cake.