This is so interesting, I found one - two the hardest. I honestly assumed it would be a doddle, we had had a prem baby first time around and so that was a shock to the system.
However like lilysmum I wanted a life outside of being a mother, I am a full time working mum and dh and I do go out etc. With 1 I could get babysitters more easily and she came with us whenever we went to someone's house for a party - she slept in her pram until she was 15 months old very easily.
Like Codswollop said with one, the other can get a break sometimes and I have a dh who is happy to look after my girls.
However with two, it is so much harder, particularly when they are both screaming at once, you feel so pulled in every direction and it seems impossible to prioritise which child needs you more!
I knew what I was letting myself in for as far as the basic looking after a baby went, but wasn't prepared to need a million hands to cluch two children, handbag, baby bag, coat of the toddler and her toy monkey, the car keys and a buggy in the middle of a crowded and busy car park!