So, I can find plenty of bags that fit the first two requirements (fits camera gear and laptop), but I'm having a hard time figuring out whether the third requirement can be met, basically because I can't test it. I've been looking into a Lowepro Classified 250 AW (I've tested a 200 AW, which appears to be the same thing without the extra space for a laptop). I know that it will be able to all the camera gear with which I travel, plus a laptop cables and so on. What I can't figure out is whether it will fit as an under-the-seat "personal item" in an airplane. I currently use a laptop backpack and cram my camera bag inside of it. I've never had a problem carrying it on as a "personal item", but everything is crammed in far too tightly. Any suggestions?