I'll second the above: when I travel light, I take my 18-55, 55-200 and 35 f/1.8 DX lenses as a lightweight trio that covers 98% of my needs, my D5100 body, a P7100 and an SB-400. The lenses are all surprising performers and sharp, and with a D3x00 or D5x00 body, the entire kit will set you back between $800 and $1600; less than most people spend on one body.
The 18-55, 55-200 and 35 f/1.8 all take the same filter size and caps, which makes things easier when walking around and packing as I don't have to carry multiple filters, and the P7100 takes the same battery as mentioned (so does the P7700, by the way) which simplifies what I have to pack in terms of chargers, and means I don't have to carry two sets of spare batteries with me all day. They can all go in a pretty small bag together (although I have a small shoulder bag for the DSLR and an even smaller LowePro Apex strapped to the side) - it's also about the limit of what I'd throw in a shoulder bag. When I go out, I can go really light with just the P7100 or carry the whole kit if I want to, so it's flexible for anything I want to do when traveling.
Oh, also, for what it's worth, the P7000 and P7100 both have affordable waterproof housings, making it an even better vacation camera than I initially thought.