It's bigger on the inside than it is on the outside is what everybody says upon entering the Tardis. While it is quite large it can feel pretty small with all of the people that are packed inside. Sure their not all there all of the time but when they are it's best to just find one spot and make yourself comfortable there. The doctor made friends everywhere he went, well they felt lucky that every single friend he made didn't live there or there would be some real spatial issues. But the doctor had a few people that he felt especially close to and once you were there, well, how were you supposed to leave? Luckily for them though they all got along very well and were like one big happy family.