When packing for a vacation you should first consider what your priorities are for the trip. The number one consideration on what to pack for a vacation is your mode of transport: Will you be traveling pre-dominantly by self-drive car? public transport? Are you arriving on a cruise and unpacking once or are you taking a fast moving bus tour that will see you packing and unpacking every day or so? Your primarily mode of transport is actually more important to how you pack than how long a trip you will be on: I can travel with the same amount of gear for 6 months as I need for a week-long vacation. So having decided on your main type of transportation here are some thoughts on what sort of luggage you should be using:

Vacation Packing for a Cruise Vacation:

This is the easy one: you only unpack once when you get to the boat. I'd sugest though that you don't get a super huge suitcase because you will have difficulty getting it in some of the smaller cabins. Also remember to make sure its legal on the plane if you are flying to your first port.

Vacation Packing for a Self-Drive Vacation

If you are doing a lot of driving I generally find soft-sided luggage is the way to go; you will find them a lot easier to fit in the vehicles trunk space. Also several smaller pieces are sometimes easier to manage rather than one large case.

Vacation Packing for a Walking Vacation

Even if you don't think you are going on a walking vacation you will find yourself engaged on one if you catching public transport at your holiday vacation. Leave the suitcases at home in this case. Instead you need a well-fitting backpack or possibly a shoulder bag. Suitcases were never designed to be carried in length of distance. The rolling one's are marginally better but still difficult to manage.

Even if you are taking a coach tour in somewhere like Europe be aware that you may well have to carry your own bags. It's also common for hotels in Europe, especially the older one's near the centre of town, not to have lifts. You need luggage that you can carry yourself up 2 or 3 flights of stairs. One time in Portugal it was 5 flights; there was a lift but it was out of service for the week we stayed there. It was an excellent boost to our fitness!

Don't fall into what I call the "tortoise phenomenon" you know the European backpacker who you can't see for the size of their 70 or 80litre backpack! You definitely want a pack which is wider than you or one that sits above your shoulder. Have you ever been caught in a bus door by your over-wide pack - not a good look in the morning rush hour!

Ideally your pack should be carry-on size: that means it can sit on your lap comfortably if you are on a crowded bus or train. You can easily carry it for hours and yes you can fit everything you need it 30 litres or less!