Parties to Go is a great place with which to work if you are doing a large formal, or not so formal event, where you need to rent tables, chairs, tents, etc. They are geared toward these specialties and have tons of accessories in their store to appeal to all styles. Their prices for general party supplies, plates, cups, kids birthday items, etc. are quite high. I wouldn't shop there for general party goods.
They have in the past also rented costumes, which is a good thing to know. You never know when you need a duck or gorilla costume!