Hi GITU,
My husband and I did several multi flight, planes trains and automobiles, type trips when my kids were this age. It is challenging, but not impossible. The tricky thing about 1.5 years is that they are so mobile and I strongly encourage buying the extra seat if possible. We did not do that, and in retrospect I wish we had.

Is the pack and play necessary? Could the hotel not provide a crib? Perhaps you child is different but my kids never really got a good night's sleep in pack and play (despite my trying to get them used to it prior to travel).

My husband and I gave up on business class and now only use it if we go away for a weekend without the kids. As busy as we were with the kids during the flight, we just found that it was a waste of money (or points). Having access to the lounge was nice though.

I like that you are staying in one place for 2 weeks. Prior to kids, my husband and I would move to a new place every few nights. This is a behavior we had to change because it was just too disruptive to change hotels all the time with young kids. Furthermore, where before kids we would plan 3 outings in a day, now 1 activity was plenty.
I have a website where I share tips on travel with kids. It is called http://pintsizepilot.com. See the section under "tips" in the top menu. I hope there is something that may be of some help to you there.

Good Luck !