What camera? - Landscape/cityscapes

I'd appreciate any  - informed - suggestions to do with my forthcoming purchase of a DSLR camera  and lens.

I'll be using the camera for mainly landscape/cityscape shots (approx 200meters x 100m detail and field).

I'm not a very technically inclined person ( no geek) so "ease of use" is a very important aspect when considering a unit.

I have used in the past an Olympus OM2 ( 25 years ago and not very succesfully) and I currently use a little Canon Powershot.I'm looking at uping my camera time and commiting myself to this making it a serious hobby.

My local camera shop has suggested a NikonD90.

Thanks for any advice.

momo55