We have 5 budgies and 2 cockatiels. I built them a large wooden cage the size of a fridge, with plexiglass for two of the sides and the front, with a plexiglass door as well. Oddly, the 'tiels and 'keets get along just fine in the same cage.
Both of the 'tiels are friendly, but Lemon is the only friendly budgie. He'll let you do just about anything with him, and if you're laying down and make a kissy face, he'll crawl up to you and peck your lips with his beak.