I highly reccomend Sovereign Hotel if you're going to Prague. Nicely designed room, great location just a short walk from museums and restaurants, still the street outside was quiet. We really liked the breakfast; different bread and fresh fruit every day. Maybe not a hughe variety to chose from, but there was definitely good stuff to eat (even for me who is a vegetarian). We also liked the fact that the hotel wasn't that big - the overall feeling was intimate, and the staff acted friendly and helpful.
Don't miss the local pub Ferdinanda on the corner opposite the hotel - not fancy at all, and mostly visited by locals - but they have wonderful Ferdinand beer, if you're into that.
Overall, our stay in Prague was fantastic, and I would definitely visit Sovereign again!