ditto on the nursing/bottle/paci on take off/landing... though crying also helps their ears regulate to the change in altitude... so if he does cry it is usually brief.
though stressful for you, it is actually much easier to travel the smaller they are... plus the vibrations usually make them sleepy.
most airplanes have a flip down lid/changing table in the bathroom (behind toilet). it is awkward & small, and hard... but better than trying to do it on your lap. if you do need to change a diaper in your seat, just make sure you have lots of wipes... and pack a few extra gallon sized ziplocs to store the dirty ones. (and clothes if you have a blow out). you and your fellow passengers will be thankful for the nearly odor free storage.
also, bring a change of clothes (or at least a shirt for you) for you and your baby. my daughter is not a barfer, but she has puked on me or my husband every time we've flown somewhere. a few extra burp cloths and some of those receiving blankets are good for wiping up messes too or puttinh down when surfaces aren't so clean.
bring a sack full of toys, rattles, etc... pick up a few new ones that your son hasn't played with before. trust me anyone who is sitting near you would rather hear a toy (as long as it isn't battery powered and noisy) than a fussy kid.
i will also admit to not being above bringing along some liquid tylenol... i am not sure if the altitude gave my daughter a headache or what... but if your baby gets super fuusy... you might want to have some on hand.
as for seating, since most airlines seem to have done away with assigned seating, i try to sit next to an older woman who looks like she is a grandma or any woman who has that "mom" vibe... wrong to stereo-type, but i sat next to a lady who played peek-a-boo with my (at the time) 6 mo for nearly 2 hrs straight. i don't know who had a better time... my daughter or that kind lady.
remember to pre-board... and you can gate-check your stroller/car-seat, it doesn't count as a carry-on item and you can use it again as soon as you land.
flight attendants are usually unbelievably helpful, esp if you are traveling alone... just ask for help if you need it. (one held my daughter when i had to go to the bathroom... i could have kissed her).
traveling with small children is a lot of work... but you won't believe the kindness of strangers... kind of restores your faith in humanity. perfect strangers will hold open doors, lift your carseat on to the security conveyor belt, etc...
whew! sorry to write a novel about this.
good luck!
p.s. make sure to wear slip on shoes for security... and no belt or other items you need to remove, etc. anything to make it easy to get through security. Also make sure to bag up (again in ziplocs) any formula you have. though expensive i liked those single serving travel packs of formula. they are easier to get through security than baggies of formula.