My son is much better when he's around other people. He always was, even as an infant.
I was petrified about having another because he was so much work. But actually it's even really ok. I don't know if it's because the second baby is an easy personality in comparison, or whether I am not much more experienced and that makes a lot of difference.
I was always told that it's easier to have 2 of your own because if you don't, you'll spend your time either being the playmate, or arranging a playmate to come over. And it can be much harder to enforce your home rules with other peoples children not always, but certainly sometimes
My family have had decent gaps between all their kids and the older children like to play 'Mum' with the younger ones. While they shouldn't be used as childminders, it does sometimes help a bit, and they are entertained while doing so as well!
Of course all kids are different and you never know what temperament and personality you'll get, but in really glad I went for two and its really not as bad as I'd feared.
Maybe it helps not having 2 in nappies and such like though?