Need a clean, affordable B & B, Pension or Gasthof in Garmisch-Partenkirchen, a family of four... for a few days in April.
Try the Fraundorfer:
We stayed here on two separate occasions. Very friendly hosts and the rooms had a lot of character. The rooms have beautiful views, and last time, we had a balcony and could see the Zugspitze from our room. Nice little breakfast in the morning. They have several different room types (which are shown on their website) which will probably accomodate your whole family! http://www.almenrauschundedelweiss.de:80/
Another endorsement here of the Fraundorfer; stayed there last summer and thought it was fine. Since it hasn't been mentioned yet, at least one nite of your stay have dinner downstairs in the restaurant. Good food (if the white asparagus is in season, GET IT) as well as a show with folk music.