I'm all in favor of vaccinating, for lots of the reasons listed before. Polio = bad. Small fever = Tylenol and all is well.
As far the schedule, I know that part of it is that they space it that way so that kids can get the max coverage as quickly and safely as possible.
Hepatitis B - Hepatitis is just a generally nasty thing to get. This one I don't know why it's birth, two months, etc.
(2 months)
DTaP - diphtheria, pertussis, tetanus. 3 nasty bacterium that you really don't want to get. They need regular boosters*
Hib - next dose!
Polio (IPV) - sure, there may only have been two cases, but who wants to be case #3? No, thanks. The vaccine is so effective that why not go ahead and avoid a lifetime of pain?
Pneumococcal (PCV) - primary cause of meningitis in kids under the age of one. It's deadly, it's nasty, and it's preventable.
Rotavirus - severe diarrhea in kids is problematic; their immature systems dehydrate much, much faster than adults. And when a kid goes into true shock, it's scary.
Why do more vaccines kick in at 2 & 4 months? It's partly due to the fact that at 90 days of age the baby's own immune system is finally starting to work. Baby no longer has the antibodies from mom (from before birth - will still have some via the breastmilk if breastfeeding)
(4 months) - rinse & repeat.
DTaP -
Hib
Polio (IPV)
Pneumococcal (PCV)
Rotavirus
(6 months)
DTaP
Hib
Pneumococcal (PCV)
Rotavirus
(6 to 18 months)
Hepatitis B
Polio (IPV)
(12 to 15 months)
Hib
MMR -
Pneumococcal (PCV)
Varicella - optional, in my opinion. I haven't seen chicken pox in my ER in years. Lots of folks think they have it, but it's almost always ended up being a different kind of rash.
(12 to 23 months)
Hepatitis A - icky disease. All hepatitis-es can have a chronic effect on the liver; you kind of need the liver. I'm a fan of the a/b vaccines.
*DTAP - while studying antibody levels, they're discovering that the vaccines for pertussis, in particular, doesn't last as long as they thought it did. It's also not as strong as they thought it was. However - I think it's still important to get. It just means, that like MMR, you may either need a booster or to get your titers drawn to see if you're still immune. However, if you're a little one, the vaccine is less invasive than drawing titers, so they tend to just do that.
As far as the HPV vaccine, what I've read on it is fairly positive. I'm a fan of that one as well.
Then again, I like vaccines in general. I hope that helped.