Nikon - FTW!
if you are to spend like crazy - dump money into lenses, not the camera body. lenses retain their value fairly well, the camera body - not so much.
a grip is not needed, especially on a beginner camera. if doing an actual shoot (wedding, etc) you might wish you had one. for your purposes, not so much. an extra battery might be helpful - keep a charged one in your pocket.
stay away from uv filters and polarizing filters... they do VERY specific things, and "protection" is not one of them. millions of dollars are put into research and development of how light enters the lenses, pass through the 7 or so pieces of glass on the inside, and makes its way to the mirrors. dont slap a cheap 5$ plastic filter on the end of it - light will not enter quite the same way. i have a couple of lenses that have been banged up on the lens itself (small nicks & scratches)... when taking a picture, you will not be able to see any indication that the lens is "less than perfect", as the scratches are well outside of the depth of field. i would rather use the lens hood that comes with the lens for "protection". but...this is just my opinion - you might not notice any difference with a filter on the lens. if this is the case, by all means, go ahead and slap one on the end of it.
unfortunately, photography is not cheap. you truly get what you pay for. for example, a 50mm f1.4 prime can cost up to 2000$, while a 50mm f3.5 prime can cost 200$ (as an example - not sure if they even make the latter). you will have MUCH more flexibility with the first lens (being able to shoot in darker conditions, more narrow depth of field, etc). however the second lens is much more budget friendly. do these matter to you? i cannot answer that. you may be very happy with the second lens.
just fyi: prime lens = fixed focal length (meaning... your legs are used to zoom in and out) ... as opposed to a zoom lens (self explanatory)
buy multiple SD cards. as you are on vacation... shoot a ton of pictures, delete the crappy images when you get home. multiple SD cards will give you tons of space to work with. also, make sure the SD cards are at LEAST class 6..... class 10 is ideal. (higher class will allow data to be written to the card much much faster, as well as faster read rate when transferring to a computer later)
if you are "just taking pictures", shooting in Auto will be fine, and you wont need to dump money into lenses.
the next step - *IF* you want to start getting more "artsy" or just want to become a "power user" of your camera - is to figure out how aperture, shutter speed, and iso affect images - both for good and bad, and also how to manipulate these quickly on your camera.
also, learn to FRAME your pictures. no matter how good your equipment is, it is only as good as the person behind it.
FWIW - i have shot two handfuls of weddings and am now also testing the waters of head shot and portrait photography here at work. i also travel - a LOT - these are just a few of the things i wish i knew when i started way back when...
I want to get some practice, so I ordered it early.
