here's my $.02 on the topic
i just got back from a european tour, this is what i did.
pelican case 1500 for my motu ultralite, some pedals, cables, korg nanocontrol and akai lpk25
mono case "the producer" carry on bag http://www.monocase.com/mono-efx-producer.asp
for laptop, other cables, headphones, books, other junk.
you could get a pelican case with a laptop bag built into the lid (an option for their 1510 rolling case which is awesome among others) or a bigger pelican for everything and just have a small computer bag to carry on your laptop.
NOW, for the guitar. Oftentimes, airlines will try and charge you oversize to check a guitar case, truth is, most reasonable guitar cases (not big coffins, or pointy things) will fit in your average international overhead bin. They will not however, fit in the overheads on smaller connecting flights. I got a mono guitar case http://www.monocase.com/mono-electric-guitar.asp
and have used it to fly around southeast asia and europe. it's a really sturdy softcase, so it protects more than any $50 guitar center bag, but because you can wear it like a backpack, airline folks are more prone to let you carry it on vs. a hardcase that they don't think will fit through the Xray at security.
most airlines let you carry on a guitar or bass in a softcase as part of your allowed carry on. If there is no overhead space, they'll sometimes put it in a storage closet on the plane (so be nice to your flight attendants) it also helps to get to your gate early so you're one of the first ones on the plane.
my suggestion is to check your clothing bag and a pelican case of your gear, and carry on your guitar and laptop. you'll probably have to pay $30 for the second checked bag, but if all your gear fits in something the size of the mono producer bag, carry that and your guitar on and check your clothes.