The Hotel Belvedere is a beautiful chalet-like building in the centre of Semmering. I travelled there by train from Vienna (the train journey itself is highly recommended with great views), but would suggest getting a taxi from the train station to the hotel upon arrival in Semmering unless you have no or little luggage as it is quite a steep walk to drag a large case as I did! Once installed, there is a supermarket two doors down from the hotel for those packed lunches that you will no doubt want to take up into the mountains, accessible by the cablecar which is just 3 minutes walk from the hotel.
Staying at the Belvedere felt like being a house- rather than hotel-guest. I had a large, very comfortable, high-ceiling-ed room with flat-screen tv and balcony looking out up into the mountains. The owner met me himself, emerging from the kitchens, since he is also the main chef. I dined in the hotel restaurant on the night that I stayed and the food was very good. The breakfast the following morning comprised a very good and homely spread - no complaints at all!
The "house-guest" experience was finished off by being driven by the owner of the hotel back down to the train station rather than making me take a taxi!
I would definitely stay at the Belvedere again.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC