Roses are a good source of pollen and nectar - not a top 10 source - but its nice to be able to have some 'showy' plants in the bee-plot that are good for the human soul too. The critical thing is the type of rose; they must have an open flower (like this one in the picture) where the bees can easily get into the centre. The ones with the highest amounts of nectar tend to be species roses like Rosa acicularis which is the indigenous European rose or the more commonly found hedgerow plant Rosa canina or dog rose. These are available from most places that sell hedging plants.
David Austen sells a good range of nice species roses but avoid anything with a double flower.