Do you have a baby carrier? Check out www.heavenlyhold.com or www.frogmama.com for some ideas on wraps, slings, soft structured carriers, etc. This would help you keep the baby close and keep strangers' wandering fingers and curious germy mouths away from the newbie....BTW - slings are safe with proper use! The ones to avoid are not sold on either one of the above sites that I mentioned.
At the same time though, I wouldn't worry too much about germs, as long as no strangers are touching the new baby, and you are all washing your hands diligently. (I will say that I found that my 2nd and 3rd kids got sick sooner than my first -- the big ones are germ-magnets!)
I LOVE the AA children's museum! Or, how about ice skating or Jungle Java or Open Gym at a gymnastics place? Chuck E. Cheese?