What sort of use? What are you replacing?
For general riding around I have the LBS build me some wheels, e.g. Mavic open pro rims on 105 hubs, however everytime I've done this I've either been upgrading some cheapish wheelsets or building a bike from scratch. I don't race, except 'cross.
Going from something like a set of Shimano R500s I find them a considerable improvement, but I don't know how they stack up against the more performance oriented budget wheelsets.