Is it a holiday? I agree a sling is the best way to go, they keep your hands free - also although the taxis say they have seats for bubs they are really hard to get. The sling comes in handy there too as you can have bubs close to you if you choose to take a taxi without a seat. I thought WTF when the taxi lady said "sorry no baby seats available, but you know legally you can hold him on your lap"!!! If it's a holiday & you're staying at a hotel find out prior if they have a porta cot you can use, saves you taking one along. If you are going for a while & want a pram a cheap stroller is a great idea. They pack up heaps better for taking in a taxi & to the airport & if they get broken in transit it's not such a big deal. Otherwise if you want to take a big pram putting it in a bag of some sort first would be good, we also used zip ties to make sure ours didn't unfold. I took my baby bag as carry on luggage, had all the gear incl bottles. Lots of people say to feed bubs or give dummy when taking off & landing....my bubs didn't even stir either times so I was very lucky. Or you could massage just in front of bubs ears, that's supposed to help too.
Just hope & pray bubs doesn't decide to do a big stinky no2 up in the air, those change tables in tiny little toilets are horrible! Charlie was only 6wks when we flew back to WA & I was just getting the hang of the nappy changing, but doing it on the plan was a challenge in itself....think it took me 20mins LOL.
Hope that helps.