hey guys,

ive got a trip coming up and would like to get some better gear for my canon 450d, im currently just using the standard lens.
ive got two lenses ive decided on getting. option 1 is the sigma 18-200 (OS), and option 2 which is the sigma 17-70.

which of the two would be best suited for landscapes, and portraits? originally i wanted the 18-200 because its so versatile, with a much bigger range and bang for buck wise it would save me alot of money rather than buying multiple lenses to cover the range from 18 to 200.

because im going japan, is it actually cheaper to purchase the lenses in japan considering its made in japan. any good places to buy camera gear in japan? im mainly gonna be around tokyo city.

which lens of the two is best suited for my trip?
which of the two lens are actaully better?
which one of the two are more bang for buck?

any suggestions? pros/cons towards these two lenses? im quite new to all this so your suggestions will help me heaps.

thanks!