I'm booked on an Alaskan cruise in May and I wondered if there was any "must-have" equipment I should pack in my bag? We'll be cruising Glacier Bay and the Inside passage with stops in Juneau, Skagway, Ketchican and Victoria, BC. We have a mini-suite, so have balcony access throughout. We are flying to Seattle, so space is limited. I have my XSi along with 18-55 and 55-250 IS lenses. Everything has to fit in my Lowepro slingshot 100 bag. Comments or suggestions?