M.K.
I really like the advice Laura S. gave - we did similar things with our first two, who were 21 months apart, although a little less playing at being the baby just because my daughter was older and seemed to need it less than she would have if she were 14 or 15 months old. I will say that the first month was pretty rough, but they are best friends now and I love seeing them play together. It's actually harder to have one of them home alone than to have the two of them together, because when they are both home they entertain one another. When my daughter's friends come over for play dates my son plays along (thankfully my daughter's friends are usually really nice to him), and we've lucked out with a couple friends who have two kids who are similar ages.
Good luck! We're having our third in a few weeks, so I'm facing my own challenge with three where the oldest will only be three and a half...