I went to both the Seychelles and Mauritius last summer and enjoyed both very much. The Seychelles overall have prettier beaches and somewhat better water, and are more of a quiet place with little to do except relax and "get away from it all", but costs are generally much higher price than Mauritius (I would say overall roughly double or more). Although Mauritius has more urban areas and caters more to the mass market, I still found it incredibly enjoyable. The scenery is spectacular, the culture is very interesting, the people are wonderful, the prices are reasonable, the food is good (and varied), and especially if you rent a car, you can find secluded, beautiful beaches to get completely away from the crowd. If you want to visit both places in one trip (and if you're flying that far, why not?) you can book it as an open jaw on British Airways, for example flying into Mauritius, returning from the Seychelles, with a stopover in Nairobi either going or coming. (I did this on a British Airways frequent flyer ticket.) You can book a one-way ticket on Air Mauritius between Mauritius and the Seychelles for about US$170 (This fare is not offered thru any of the online booking services. You have to call Air Mauritius directly. They have a phone number in the US).