Chop it and freeze it to use when you want to fry up some carrot and celery and onion as the base to a stew or soup. Include the leaves, they give a nice flavor too.
Keep the tenderest sweetest pieces near the middle, with their leaves chopped off, in the refrigerator, wrapped in foil to make it last longer (I hear).
When buying celery, I smell it. If it smells bitter, I don't buy it, when it smells sweet, that's the good stuff.
Celery is a running joke around here. I cook dinner for a friend that HATES celery. Everytime he asks about dinner, he says 'what's in it'?', I always reply with 'A cup of celery' (he hates it), 'A cup of jalapenos' (hates those too)....., his eyes grow big, and of course there usually isn't any celery or jalapenos in it......and then we all laugh.