If you want nice accommodation, friendly, helpful staff, then Karlova Apartments are the place to stay. We used their airport pickup service with our driver there on time to pick us up from the airport. Our check in went smoothly and we were soon in our apartment. Two & half bathrooms which were very modern and the bedrooms were more than big enough for the 4 of us. Kitchen was very small but as we only prepared our breakfast in there it was passable. One of the best thing for us being on holiday was that the apartment was cleaned every day - no housework!
The location is the best with being in the centre of old town. We walked to all the attractions or MUST SEEs of Prague. There were many restaurants around, if you walked a block or two from the apartment the prices were very cheap.
We only had one hiccup, and that was the day we arrived the lift was broken but the staff helped to take our bags up to our floor. It was fixed next working day.