When the kids have birthdays we follow the American style of inviting to the party from and exact hour to another exact hour (two hours after in Kansas and three hours in Colorado). During those hours we program activities back to back in a very scheduled fashion. We spice it up with a real Piñata (not the Party America kind), some craft or activity in Spanish and at the end the Happy Birthday sung the Guatemalan way. The first party my parents were here with us they had a blast watching the dynamic. At five minutes before the starting time I said "Watch all the guests will arrive in the next five minute" and sure enough. Five minutes before the party ended I said now watch how they all we'll all be gone in 10 minutes, and sure enough!! It is not what we are used to, in Guatemala if the party is at home people will come around the hour you invited (plus 30 to 45 minutes) and you just plan to have some people stay until
dinner and for dinner. All your extended family is invited even if the kids aren't the age of the birthday girl/boy, and you expect all the family members to come. Even as we get more Americanized and have birthday parties at a party place, people will end up at your house later.
In order to satisfy our multicultural household we do the American Birthday party and then the party keeps on going with our closest friends and their kids until whenever, with no agenda other than continuous amount of food and conversation.
When the adults have birthdays we organize our own parties (this is what my mother in law finds the funniest, she has told me that adults don´t celebrate themselves). We make a come around "x" hour to whenever type of party, bring your kids or any guests you might have at home they are all welcome. The Guatemalan spirit truly is "the more the merrier" or as we would say "le hechamos mas agua al caldo" (we will just add more water to the soup).
Various of my children's birthdays we have spent in the US so I had to teach the girls' classmates how to sing the Guatemalan version of the Happy Birthday. When we celebrate either one the kids birthdays or ours, the guests know they are undoubtedly going to be asked to follow something in Spanish.
This is how it goes. The firts part is sung in English with a beautiful Guatemalan accent. Happy Birthday to you, Happy Birthday to you, Happy Birthday dear Alex, Happy Birthday to you. Then comes the second part to the same tune (usually clapping to the rythm) Y ya queremos pastel, y ya queremos pastel, aunque sea un pedacito pero queremos pastel. (And we want some cake, and we want some cake, even if it's a small piece, but we want some cake). Some my go on to Que te bendiga el Señor, que te bendiga el Señor, que te bendiga por siempre, que te bendiga el Señor. (May the Lord bless you, May the Lord bless you, May he bless you forever, May the Lord bless you).
PS2! I just found this website with a funny and very realistic description of a difference between an anglo and a latino birthday party. Click here.