BP-certainly for younger people. Try to buy one-if not yet having-one that is sized so that you can also easily use it to go onboard planes as hand luggage. Those hard plastic ´flite cases´ on rolling wheels are just a nightmare for use in trains/buses

PS-the tipical 1st time young newbee IR-user was comically always shown as carrying a giant super-over-sized bekpek, with 2 stinky sneakershoes bungling from it, a pek often even larger as her/himself. be smart-you can do with less.

Hi David,

I forget what they’re called, but a lot of people swear by those very commodious rucksacks with another mini day bag zipped to the front. If you have one of those you’ll have enough room for everything you need for your trip, but can leave most of the cumbersome items in your ho(s)tel room when you go out sightseeing for the day.

I'm not quite so young anymore but I always use a backpack because then I have my hands free.

Hi David, I’m in a similar position to you with my plans being later this year, I would be really interested to know what you settled on and how you’re finding it?

On many past Interrail trips, lasting from one to three months, I have taken: a good money belt; a 30 litre rucksack; and a wheeled, soft, 74 litre bag. After every trip, I vow to travel lighter next time! The hands-free money belt and rucksack are fine. When travelling between what I call 'hub' locations, they hold my valuable and attractive items securely. When 'spoke' travelling, out from 'hubs', the rucksack becomes a water- and sandwich-bearing day sack. No, it's the 74 litre wheeled bag that is too big. Being big, it tempts me to pack and carry too many 'nice to have' items, some of which still return from long trips unused, even now. So, I am looking to purchase a wheeled, soft, 33 or 39 litre bag instead. Such a bag will constrain my packing to essential items only and will be much easier to haul on and off trains, not to mention trains' luggage racks, which are often full in peak season. I know that laundry days eat into holidays, but it is possible to travel for months with only 8 changes of under clothes. An increasing number of hotels offer guests washing machines these days, especially in Scandinavia. Elsewhere, I research laundries on Google near my chosen hotels in advance. For all those other 'nice to have' additions,  besides 14 changes of underwear: improvise, barter, trade, borrow, swop or simply buy items that turn out to be essential. Whatever you do, travel light! There may well be times when you have to run with your luggage through crowds, up and down steps; for example, when platforms change at short notice. 

On reflection, there's more to the suitcase or backpack dilemma. Whichever you choose, think about bagging items inside your luggage too. As a liner, I generally have a large, robust, transparent, plastic 'bin' bag. There's little worse than arriving at your next destination hotel, to find that most of your possessions are soaked through by rain. The transparency of this bag allows me to find odd nick nacks, without too much rummaging. Within the outer bag, I generally have a number of smaller, differently coloured bags, positioned as to the likelihood that I will need them. So, in the bottom of my luggage, I will position essential items that I am unlikely to need. At the top, I will generally position two bags: one with overnight gear (PJs, phone charger, toothbrush, night lights etc) and one with the clean clothes that I will need in the next 3 days, say. That way, I can arrive tired at a hub hotel, unzip my luggage and (within 20 minutes) be in bed ready for breakfast and several days of sightseeing. For me, vacuum bagging to conserve space is too much of a faff. I prefer instead inner bags of different sizes and shapes, and some that will constrain ironed items, to prevent them from creasing. You might find that one or two cotton tote bags will double up: as inner bags and food shopping bags. And, do consider packing a few, nylon, draw string bags to store, hold and transport your dirty washing around laundry days.