booster seats for travel

[enc3]

I'm searching for a portable booster seat for travel in planes and playdates.
I have three boys, one will turn 7 in March (46 lbs and 45 inches), a five year old (44 lbs and 43 inches) and a 2 year old who is 30 lbs. In the past we have traveled with two Graco Ultra Cargos and a Britax Roundabout, lugging all three carseats through the airport. Now that my older boys are bigger and have outgrown the harness option for the UltraCargo, I'd like to find a lighter, more portable option. I looked in to the Graco backless booster, but am nervous it isn't safe enough for all the driving we'll be doing on vacation this February. Ideally the booster seats would also be convenient to use for playdates in other people's cars; i.e. easy for other parents to take in and out. We currently have the two older boys harnessed each in a Britax Husky in our primary car, but this is not an option for travel for us.
Is there anything out there? We still plan to use the Roundabout for the two year old.

Thanks,
Emily

[Joolsplus2]

What some people do is buy the Highback Turbo, and then separate the back, and pack it in a duffel bag and check it through, then bring the backless on the plane as carryon. That way, if you get to your destination and your luggage is lost, you at least have the backless so you can leave the airport safely, but you have the option of a full back for the trip, or a no-back for ultra-convenience (highback seats are definitely the safest, particularly in side impacts, but even the best of us use no-backs from time to time out of convenience). Some people like the Parkway, and just stick it in a carseat travel bag and either luggage check it or gate check it (it's not separatable, but is smaller than the roundaout when bagged up). The Compass B510 is a decent choice, but I hear it has quality issues... I think they have a good warranty if the cover gets funky, though. The Safeguard Go is a harnessed seat to 60 pounds, then a booster to 100, but it's complicated to use for playdates. The Ridesafer travel vest is the easiest to travel with, but kind of a pain for others to use properly and not so great for sleeping/no side impact protection.

Hope that helps, try searching for other posts on these to get more info, or ask away, all questions are good.

Kudos to you for traveling so safely! It's such a pain to bring seats, but so worth it in the end :)
Julie CPS Tech and mom to 3 in seats
http://www.cpsafety.com/articles/RFAlbum/SarahMA.aspx

[enc3]

Thanks for the advice. I'll look into the Parkway or Turbo.
Emily