There are plenty of nice hotels in Stockholm to choose from. Some of my favorites are Rival at Mariatorget, the centrally located Grand Hotel and Hilton at Slussen.
If you want a really central location, near the Central station and Arlanda Express I can suggest the Nordic Sea Hotel with The Icebar. Other centrally located hotels are the Nordic Light Hotel with its modern style, the classic Sheraton or the large with a bit more anonymous atmosphere Radisson SAS Royal Viking hotel. A nice and intimate hotel in the same area is Freys. Sergel Plaza is another nice and central hotel.
Scandic Park Karlavägen is a good choice on Östermalm and nearby is also Anglais. Elite Hotel Stockholm Plaza is a more personal choice in that area and the same goes for Hotell Kung Carl and Crystal Plaza. At Nybroplan you will find exclusive Berns, a hotel of distinguished heritage. Another modern hotel with a historical touch is Hasselbacken at the Kungliga Djurgården, next to the Cirkus Arena.
If you want to stay in the Old Town I can recommend the very nice Hotel Reisen and on Södermalm you will, apart from Hilton och Rival, also find Clarion. Next to the Globen Arena you will find Quality Hotel Globe. On Kungsholmen I can recommend Amaranten and in Vasastan Elite Palace. At Norrtull, next to Karolinska University Hospital, you will find Stallmästaregården with its classic restaurant.
Not far from the central city and in touch with the archipelago you will find Yasuragi Hasseludden and Grand Hotel, Saltsjöbaden.
If you have plans to take me to a nice dinner I can recommend a few restaurants. But don’t feel restricted by my suggestions. I like almost everything and like to try out new restaurants. If I choose there will often be fish and seafood or Italian food on the menu. I also like Thai and Indian food and I like it hot.
A very good restaurant that I often come back to is Wedholms Fisk at Nybroplan. The KB, Konstnärsbaren, close by is also a favorite. You can have a real exclusive dinner at Esperanto - probably one of Stockholm’s best restaurants and another suggestion is Rolfs Kök. If you stay in a central hotel I can recommend Stockholm Fisk in the hotel Royal Viking.
In the Old Town you should of course pay a visit to the classic Den Gyldene Freden dated back in the eighteenth century. Classic in another way is Nalens Restaurang that’s like “the restaurant on the corner” and serves good tasting food. Karlsson & Co have quite a lot on their menu if you want to dine next to one of Stockholm’s best dance floors.
If you like beer or whisky I can recommend Akkurat by the Slussen or Duvel Café on Vasagatan. Both places serve good clam stews. Small cozy Italian restaurants with wonderful food are La Famiglia, La Tentazione, Il Conte and La Cucina. A good Chinese restaurant on Södermalm is En ful och en gul and if you want Thai food I will absolutely recommend Naviya. The Thaiboat can be a nice alternative, especially in the summer.
In the summer I can suggest a trip to Drottningholm Palace and Drottningholms värdshus or to Fjäderholmarna next the archipelago of Stockholm. Both are best to visit daytime because they close early.

If you are looking for a hotel with reasonable room rates I suggest you visit the web site Destination Stockholm where you can also find more recommendations on restaurants.