I wouldn't do it for a two hour flight.

2 hours? No way. Waste of money.

I would absolutely buy him a seat. You intend to hold a 16 month old for 2 hours on a plane. You are insane. You have no idea if your child will be a wild child or a complaint child. If you have a child who squirms and won't sit on your lap it sucks to not have his carseat on a seat (trust me). If you feel you want to wing it then don't buy a seat, but I honestly feel it's a mistake. Also, depending on how crowded the flight is you could take your chances that an empty seat will be available to use for him (although these days I would not trust that b/c all flights I've been on lately have been booked solid).

I would not spend the money on the extra seat. Two hours flights when DS was that age were okay. 3 hour flights were a little more challenging. Doable if you are well prepared with fave snacks, new books, ipad, etc. Window seats are good for the time before takeoff "look at the plane, look at the truck..."

We always bought a seat for our kids (2 of them).

I wouldn't buy him a seat. Especially not for a 2 hour flight.

If I had an excess of cash lying around I would buy him a seat just to have more space to play and move around.

Think about the timing of the flight; if you think he'll nap during it he wont need a seat. If, on the other hand, it's a prime active time, having the extra room (even if he's in your lap) is really nice.

~ mom of a active, antsy, 18 month old, without a money-growing-tree but finds it a worthwhile expense for our sanity on longer flights

I've been on very turbulent flights. It is scary. Buy him a seat.

Agree w/PPs -- I wouldn't buy him a seat unless money isn't an issue. It doesn't look like it will buy you an easier flight. I would, if possible, try to get bulkhead seating so there's a little room for DS to play on the floor (assuming no turbulence).

I would not buy him a seat.

As long as you're not traveling by yourself with him, I wouldn't do it for a two-hour flight. You should be able to keep him moderately entertained on your lap, especially if you have other laps he can move to. It's a tough age for traveling, and while the extra seat might make things marginally easier, I personally wouldn't find it worth $370.

People feel strongly about this issue.

For safety reasons, yes, you should buy him a seat. It's unequivocally safer. And probably easier for you (though if you buy him a seat, he has to be in it on takeoff and landing, whether he wants to be or not.)

That said, if money doesn't grow on trees in your household, the odds are infinitesimally slim that there would be any sort of problem that being in a seat would help with. I personally felt like I take risks in my life, and this was one I was comfortable taking.

Op here - we sadly still have him in his carrier (I am getting a new one any minute!), so I don't know if he'll like the new seat. He likes/tolerates it, but he's definitely getting squirmier these days and was on our last flight three weeks ago (wanted to come out of the carrier like 20 minutes into the flight).

Does he like his carseat?

Going on vacation with my family in December. DS will be 16 months, and I have no idea how much he will change in this time since he's my first. Do we need to buy him a seat (not per the airline's rules, but to keep our sanity)? It's about $370 extra dollars, and the flight will be 2 hours.

Thanks for your thoughts!