Depending on your budget you could upgrade your kit lens and go for the EF S 17-55 2.8. IS USM I think on your 400d that would give you the equivalent to 27mm - 88mm in 35mm terms. You could easily use this for landscapes and general photography whilst on holiday.
http://photo.net/equipment/canon/efs_17-55/
Or look at the Sigma version.
I replied to your post out of curiosity really, because my niece has the same name as you. But of course this is not possible that you are her, is it?
Regards
Keith Towers