I love this - I love to party plan and my grandparents loved to polka and other dances as well - they were Slovenian. Grandpa's gone, and grams is now in senior living. I could come up with an endless list of ideas if I spent a good amount of time, but here are some to get you started:
I found this Web site: http://www.cityofjoliet.com/business/tasteofpolonia.htm
which is for a Polish buffet place in Joliet that has polka music - they might recommend some bands/musicians. I see in the lower right corner of the Web page, they list a band called the Bula boys.
I know a guy - John Chernovic - who plays the accordian, lives in Joliet, he and a couple others played some polka music at a luncheon I went to. Don't have his contact info off hand, but you could look him up.
You could also check out this Web site or contact someone here: http://www.internationalpolka.com/index.html It's the polka hall of fame in Chicago.
You could look up Polish heritage or German heritage online and get some ideas of the country flower and put those on tables - maybe there's a particular baked good - kolackies - that you could serve for dessert. You could name each one of the tables at the party after a polka song or famous polka singers - Frank Yankovic, Beer Barrel Polka - I'm sure you could find some names on the polka hall of fame Web site. Then create a seating arrangement and on the name cards write the name of the table and people have to find that table name.
You could serve a classic German dinner like viener schnitzel.
Maybe give them a calendar with photos and for each month have a different picture of them through the years.
Create a list of things that were popular in the year they got married - music, clothes, celebrities, the latest rage, phrases, songs, etc. - and print it out on little cards on nice paper that you put on every seat or at each place setting. That would give everyone something to talk about also - a conversation starter.
Do they have a favorite candy? You could tie that in to the table decorations. Or a favorite drink - if they love a certain wine, serve that, if they love lemonade have pitchers of it on the table - you get the gist.
What about finding a famous German or Polish romantic poem and reading that in English to toast them?
You could tie the wording of the invitation in to the polka - grandma danced her way into grandpa's heart in 1949, come help us celebrate and dance the night away.
Oooh - you could put together a powerpoint slide show with pictures of them throughout the years, and write a basic script that you read over a microphone while showing the pictures via projector. Or, if you're not into reading aloud, you could just type text under the pictures and show the slide show, maybe with some soft music in the background. (get one of the younger people in the family to put that together - they'd probably think it was fun). You can make it sort of funny by mixing serious text or script with an occasional funny comment or picture.
Like, "When grandma met grandpa, she was immediately impressed with his many talents " - then in the next slide is a picture of him holding a fish on a line. "And he loved her sense of style" - a slide of her wearing something not so stylish. It's always good to bring on some laughs - especially if there will be some more serious moments.
Of course, you could put cameras on the table and have people take pix, then gather the cameras at the end of the event and put together a photo album for them later.
Oh - you could make an old-fashioned dance card for grandma and grandpa with a list of a handful of names inside of people who will dance with them.
Well, that's all I have for now. I should have been an event planner in another life.
