My wife and I are traveling to Spain next June we fly into Barcelona and then fly home from London (stupid frequent flier programs!). Anyway, we will be traveling with our then 15 month old daughter. Those of you that have traveled with a toddler did you bring a car seat or just rely on walking/bus/trains.
Thanks
Since we don't know what your plans are, it's hard to say what the best mode of transportation is. But won't you want the car seat for the flight? Little ones are safest and most comfortable in their own familiar seat. On another note, if you are unhappy with the frequent flyer programs, I'd be happy to take those points off your hands for you so you could just buy your tickets. :-)
You'll want the carseat on the airplane. In my experience, my kids slept much better and felt more comfortable in their own car seat. It must be 'airline approved', typically there's a sticker on it somewhere, sometimes they check for it, sometimes not. Contact the airline to check on their regulations. You can get great car seats with a stroller mechanism built in, so you can push them around in the airport, etc. The combo seat is great. On local transport, like busses, you won't need it, just leave it in the hotel.
We've taken ours on the plane. It's safer, plus it can give you guys a break. You don't want to be dealing with a squirmy 15 month old for 9 hours. You can buy bags to put them in to carry them in an airport. We've just loosened the straps and carried it like a backpack.
My husband and I traveled with my son, daughter-in-law and granddaughter last year when she was around 8 months old. We went online and bought a car seat/stroller combo. I think it cost around $400 but it was worth it for a 2 week trip and hopefully we can use it in the future. We rented a car and since we brought the seat with us we didn't have to rent one. Too bad you don't live closer; I would let you borrow it!
We've flown intercontinental with a baby once and did as suggested above - made sure the seat was approved for airplanes and used it on the plane. Another good idea is get them chewing or sucking on something from the time the door closes to level off and again from the start of decent to landing. Staying ahead of the ear pressure change is so much easier than trying to get a kid in pain to chew/suck on something.