As
gethinceri has said, weight, whilst important is not the be all and end all, although the quality of the wheels is very important, as the wheels act like a flywheel, and the heavier they are the harder it is to get the bike going. Also, wheels seem to be an area of the bike that the manufacturers skimp on to bring the bike in to a budget, which is a shame.
The good thing I that these days a good quality aluminium frame is reasonably priced, I have currently a giant defy 4 from about 4 years ago, and it is really good, giant do some really good hybrids too, which may be worth a lo. The other thing about giant is that they get wheels made by dt Swiss, so they are usually quite good for the price. Cannondale are a good brand, however, I think you also pay for the name a bit.
Good luck, I am looking at the moment, and the choice in the market place is simply staggering, and this has caused me much consternation, I think I have a short list for now though, and will be trying two of them later today, which I am really looking forward to, provided it doesn't piss down with rain!