Pondering Preschool

When should a kid go to preschool?  My son will be three-years old soon and I've found myself wondering about such things.  I'd like to say that it's because I'm already thinking about his academic career, but it's really that I'm selfish and I'd like a few hours to myself each week.  Yeah, Mother of the Year just put that bit of selfishness in writing.

A friend told me that I shouldn't worry about sending him to school this early since he knows numbers, colors, shapes, and alphabet.  I'm a little concerned that he still can't properly hold a pencil and he sure can't write his own name, but then I remember that he's not quite three yet and I figure he has time to learn those skills.  He's also still very young and very attached to me and I wouldn't want his first educational experience to be traumatic.  I clearly recall howling and crying when my own mother took me to preschool. . .that loneliness and fear of abandonment has stuck with me all these years later.

I'm of two minds on preschool.  One is that I think that academic philosophies in certain preschools are nothing but a glorified daycare.  My kid does not and will not go to daycare so it seems like I'd be wasting my money by sending him to that type of preschool.  The other is that I think that a more academically driven preschool might put too much pressure on such a young little person.  He will be in school at least until he's in his early- to mid-20s so I feel like I should let him enjoy these carefree days since they truly are the last that he'll ever have in his entire life.  I know that sounds soul-crushing, but it really is the truth as I see it.

If you sent your child to preschool, did you think it was worth the expense?  What type of preschool did your child attend?  At what age did you send your child to preschool?  What did they specifically gain/learn by attending preschool?  If you could change the past, would you make a different decision?