jewsons brick and patio acid cleaner works really well, be carefull if there is lime in the grout though.
we use a water based sealer to finish them off and they shine well, be sure to put a maintainace program in though, say 4 visite a year to re-seal. you can put a polish on the sealer if you want also to make them really shine, but be carefull if it is near a wet area like a kitchen or shower room.
regards ben