Definitely the 17 - 50. I have it and its a great lens... And i also bought a fujifilm F50fd 2nd hand to carry around. Don't have the idea of a pns being able to replace your dslr. The lx3 isn't exactly the smallest of pns. I would have gone for the F200EXR. Its cheaper too...
I would suggest you take a look at the new Oly E-P1. It would have a large sensor than the LX3 with all the attendant benefits and superior image quality, yet compact (with the 17mm pancake lens) and discrete enough for travel use.