My girlfriend and I are planning a backpacking trip to Europe in May. We have been looking all over the place for the best pack. We are both looking for packs that hold about 3000 cubic inches and has side access. We are going to be staying in hostels and hotels the whole time. Just wondering what the pros and cons would be when carrying a 3000 c.i. pack. Also any packing tips on what to pack and how much to pack would be great as well.

Hello Gator. Have you looked at some of the other posts? I can tell you that the premier info on gear around here Static, swears by the Eagle Creek Ultimate Explorer LT. He's a guy that works in the travel gear industry. This gives his word some weight. His choice of shirts takes away much of this weight, but you don't know that yet.

Here is some info:
a 3,000 ci pack = 50L
a 5,000 ci pack =85L

I carried a 85L North Face Extreme for a week in Amsterdam. It stored easily in the locker at Centraal and had plenty of room for snacks/gifts. But was a bit bulky on the trains.

If you pack smartly I have heard people get along well with a 50L. Try living out of your pack for a week/ 2 weeks before you leave home...then you'll know what size you can live with.

With any pack you'll need to wear it fully loaded and walk around with it before you buy it.
Your girlfriend may not be able to get a pack as big as yours.
If I had to do it over again I would get a pack without side pockets (easier to slide through crowds) and without a lot of straps hanging off it.