I'm booked on a cruise in Alaska in May - Haven't done one before. Most of my shooting will be from the balcony on liner as well as shore excursions - whale watches - eagle refuge, gardens in Victoria etc.
I love my 500 f4 L - but it does take a bit of effort to transport and use. The other lenses in my kit are 70-200 f4 L, 17-40 f4 L and 400 f 5.6 L. (and of course the $89.95 "nifty fifty"), plus a 1.4 TC. I'll be using both my 30D and 5D MKII bodies with Carbon fiber tri and mono. If I leave the 500 home I could probably just get by with the 10 ounce monopod.
So for all of you who have "been there - done that" is it worth carrying the 500 - or would limited opportunities for its use make it more trouble than necessary.
My first inclination is to take everything - but maybe that is not the best choice?
Leave it at home!
The question is are you going on a vacation or as a working photographer? I have spoiled my vacations and those around me by bringing so much extra stuff that I ended up not using. Now I'm happy taking my G9 and relaxing.
I would just take the 400 f 5.6L. It is one of the sharpest lens in Canon's arsenal, light, robust, a good balanced focal length when coupled with 1.6x factor of the 30D, the perfect traveller's tele lens in my view. Take the monopod and you are all set. Put the TC in your pocket in case you feel the need. Of course, since its Alaska
and you do have the 17-40, you would want to take it for the landscapes.