they're sick. AGAIN??

My toddler is a germ phobe.  As a baby he used to love to play with paper towels, wipes, Kleenex and anything that was used for 'cleaning.'  I swear there would even be times where he would purposely make a mess only to clean it up.  He still loves cleaning (he's since graduated to hand sanitizer and washing his hands a million times through out the day.) So of course I'm left scratching my head at all the times he's been sick this year.  It seems like he's been sick for a week out of every month.  The fun thing is he spreads it to his sister of course. 
I know that starting school has a lot to do with it, but the access started a few months before he even started.  Is it the multiple kid syndrome?  When it was just him and me it was much easier to keep him clean, and monitor all his activities, washing his hands and keeping him germ free immediately after every outing.  With a baby in tow, things are not so easy. 
I feel like I'm going through children's advil like its gallons of milk.  Keeping the sibs away from one another is another laughable task.  Try as I might, they still somehow find ways to swap germs.  I've been using a lot of the Zarbee all natural products but they don't seem to work as well as their heavily medicated counterparts. 
 A few months back I came across some of these honey suckers from Little Remedies that are supposed to help soothe coughs.  Back then he wanted nothing to do with them but now he loves them.  I always rub Vicks on their backs and chest and on the bottom of their feet as well.  I read it online somewhere and it sounds weird but I swear it works!  We also use the Vicks pads that go in the humidifier at night and that seems to help too. 
Watching the baby cough uncontrollably is the hard part.  The toddler can at least tell you how he feels and what hurts, the baby just looks miserable. 
We're stocking up on vitamins in hopes the extra immunity boost will help.  Does anybody have any remedies they use or tips and tricks for staying healthy with an active toddler who gets his hands into everything?