I don’t know if I’d want to chat with anyone for a whole 15 hours, but my choice would be Jeff Bridges.
Just as an off-the-cuff response, I would say Keith Richards.
Here’s the thing with these celebrities you think you’d enjoy talking to - they are pretty pissed about being stuck in coach and if they are wanting to talk it’ll be bitching about it for the whole time. No thanks.
I’ll go with Harvey and me not being the Jimmy Stewart character. Sure Harvey is huge but since only Stewart’s character can see or hear him no skin off my nose.
Let me sleep, read, listen to my music or podcast, or watch my movie please.
It’s literally been decades since I’ve sat next to any stranger on a plane who wanted to chat. I expect it’s a combination of 1) I am no longer young and cute (and therefore invisible) and 2) the advent of tablets, phones and seatback screens. Sitting next to a chatty person would be actually be a startling change.
That said, I’d be fine sitting next to my husband, of course, or really anyone else who wasn’t physically enormous (and thus crowding my space) or really stinky.
Yes. The stink just increases in enclosed spaces.
What a horror to be seated next to McStinkerson for that many hours.
The way flights are happening, of late, it’s not like you should get up and mill about.
I’d be tempted to ask if there’s an empty seat I could take. I don’t think they do that, really. But I’d ask.
I’m gonna start carrying those large bath cloths they sell. Funk busters or whatever they’re called. Just for such an occasion.
My wife.
One of my friends.
Frodo Baggins.
Jesus.
I’ll take Miss Marples. She thin and mannerly, and probably mostly will spend the time knitting.
OTOH, when the inevitable murder happens, I can play the dim-witted companion who usefully asks all the questions the readers want to know as she solves the crime by noting that while the second stewardess clearly has a motive due to her crush on the co-pilot, that’s a red herring. The murdered man had special ordered the vegan option at dinner, you see, and the elderly man two rows ahead dressed as a respectable cleric clearly has the wrong type of fob on his watch chain and besides he reminds her strongly of a previous village butcher who had this unfortunate habit of butchering vegetarian town residents if he happened to encounter them on lonely walks on the darker of the town’s lanes.
Of course, if I am the victim I won’t get to enjoy it nearly as much.
That’s a locked door(please!) mystery I can get behind.
I actually enjoy chatting with strangers, if they’re pleasant, engaging, interesting, and entertaining, like me.
So, Barack Obama.
I’ m sorry, but Jesus is already co-piloting.
Benjamin Franklin. Alive of course. His skeletal remains wouldn’t be a great conversationalist.
Sam Clemens might be good for 12 hours or so.
MacKenzie Scott. Figure there’s a nonzero chance she might decide to clear my student loan, who knows. That or what’s-iz-name, “Mr. Beast.” I’d be willing to star in a cringy clickbait “helping out a stranger on an airplane” video if it meant, again, knocking out my loans.
She is probably going to be preoccupied trying to understand why she’s on a commercial flight, and in coach class.
See, you design these hypotheticals and then tell us why we are wrong. You didnt say Pick one. And sure if you want to inject reality into this, Keillor is a big guy.But then, Keilor would be recognized by a steward, who would invite him- and his new friend 9me) into first class! 
But then injecting reality - I worked with hearing impaired people- and they could be quite loud. When a person is signing using BIG arm movement, they would sign back “Stop yelling”. Only people who havent worked or lived with hearing impaired would think they just sit their passively, quietly. They are just like everyone else. Keller not only Used Sign Language, but she also learned to talk.
And if the Ghost of someone that famous- or hell anyone at all- is sitting next to you- the fact everyone is starting taking pictures, asking you questions, etc- would be super annoying. You tried to get around your own rule of “not nobody” and in reality- it wouldnt work.
Good Choice.
Great conversationalist- he could keep one entertained for hours- but he would smell strongly of cigars.
Well, he wouldn’t be smoking. I could take the aroma of good cigars or a pipe.
Malcolm X. He’s one of the historical figures I’d most like to have met, and i bet he’d be willing to talk some of the time, and engage in other stuff some of the time.
He looks tall in photos, but that would be his problem. He was skinny, and I’d fit next to him just fine.
Tall is fine - it just means we’re not competing for the same shoulder airspace.
Robert “Scott” Carey.
He’s the lead character in The Incredible Shrinking Man.