Unless you fall into the form and function categories, for the most part, users are going to explicitly visit your particular online offering primarily as a prelude to visiting your physical store. Your website therefore must be supplementary with product listing, in-store collection and return, information about location, store opening times, and return policies, but doesn’t need to be particularly clever.
Chances are that the quality of your website will only mildly affect your online return on investment, and have little real impact on your offline market share. This is unless of course you really want to make money off the web, and are looking to compete as a true online retailer; in which case you’re better off using Tesco’s model of creating a separate and independent decision making subsidiary (Tesco.com) that will create and manage your web presence unlimited by the inertia of your existing business model.
Google and shopping bots like Kelkoo have already made the web convenient to search and bargains easy to find. This is the real virtual high street where users go to browse and look for the things they want to compare and buy. If you want to compete on here you can forget about the other real world high street retailers and start recognising that your real competition is shadowy and different and not limited to the brands you normally compete against.
In terms of targeting users that are really looking to buy online, your competition is the pure plays – the companies that specialise in online channels; and you should look to benchmark against these rather than other high street brands with online presences. If you really want your web offerings to be successful, they have to become entities in their own right; un-reliant on virtual malls, and unlimited by offline branding, market labelling or real world ways of working.