One lens

Around that budget a used 18-135mm or a Tamron 17-50mm f/2.8 should meet your needs. The Tamron would provide a faster max aperture (for low-light shooting or narrow depth of field) and is almost certainly sharper while the 18-135 would provide weather resistance, an in-lens focus motor and more range, while losing a small amount at the wide end.

Well after having a look at all the suggestions
Either the tamron 18-200 or 18-250 will suit my needs best. Not sure whether the extra focal length the 250 offers is needed. There are few of either flotaing sound on flea bay. Also my raynox dcr 250 looks like it will marry up very well.

Although it's tempting to want a single lens which does everything for travel, I hate having to walk round with a big heavy lump on the camera when all I want is something wide. For example, I find the DA 17-70/4 is really too big and unbalances the camera too much, especially if I'm trying not to look like a lost tourist.

My preference is for a smallish standard zoom (or couple of primes), combined with a compact telephoto prime - something like an M135/3.5 (200mm equivalent on APS-C) - for when I need more reach.

So much this.

18-55 for tripod scenery shots, hopefully sunrise etc

35mm for all the detail stuff and even ok for portraits, especially if you get a bit of the surrounding area in the shot.