By Rick Steves
A fundamental packing question is your choice of luggage. Of all the options, I consider only three: 1) a carry-on-size convertible backpack/suitcase with zip-away shoulder straps; 2) a carry-on-size roll-aboard bag; or 3) an internal-frame backpack.
A convertible backpack/suitcase gives you the best of both worlds — a mobile backpack for traveling and a low-key suitcase when in town. I travel with this bag and keep it exclusively in the backpack mode. While these soft bags basically hang on your shoulders and hips, and are not as comfortable for long hauls as internal-frame backpacks, they work fine for getting from the station to your hotel. And, at 9" × 22" × 14", they fit in the airplane's overhead lockers. I live out of this bag for four months each year — and I absolutely love it.
Carry-on-size roll-aboard bags are well-designed and popular. Many of my staffers prefer this bag; its compact design makes it roomy while keeping it just small enough to fit in the plane's overhead bin (if you don't stuff any expandable compartments). The advantage of a roll-aboard over a convertible is that you can effortlessly wheel your gear around without getting sweaty. The drawbacks: Bags with wheels cost $40–50 extra, weigh several pounds more, are awkward to carry up and down stairs, and delude people into thinking they don't need to pack so light. They are cumbersome on rough or uneven surfaces (crowded subways, hiking through a series of train cars, walking to your hotel in villages with stepped lanes, cobbled streets, and dirt paths, and so on) — but they're wonderful in airports, where check-in lines and distances to gates stretch longer than ever. A spin-off option is the hybrid bag, which has both wheels and backpack straps — but the wheels add weight when used as a backpack, and having both wheels and straps eats up interior space. Personally, I'd go with either one or the other.
Some younger travelers backpack through Europe with an internal-frame backpack purchased from an outdoor store. These are the most comfortable bags to wear on your back, as the internal frame keeps the weight off your shoulders and balanced over your hips. However, these bags can be expensive and are often built "taller" than carry-on size.
Base your decision on the strength of your back. The day will come when I'll be rolling my bag through Europe with the rest of the gang. But as long as I'm hardy enough to carry my gear on my back, I will.
Pack your bag only two-thirds full to leave room for souvenirs, or bring along an empty, featherweight nylon bag to use as a carry-on for your return flight, and check your main bag through. Sturdy stitching, front and side pouches, padded shoulder straps (for backpacks), and a low-profile color are virtues. I'm not wild about the zip-off day bags that come with some backpacks — I take my convertible backpack and supplement it with a separate day bag that's exactly to my liking.