This is purely semantics--there are many different ways to say this phrase. Generally, we would say the entrance to the hotel, because it hints to the fact that the entrance leads INTO the hotel. However, you could also say "of the hotel" or "at the hotel" (though at the hotel is a little vague, because there may be more than one entrance in the vicinity).
For the reception desk, I would say "I'll me you at reception" and that would be clear enough, though you could say "I'll meet you at the reception desk inside/at/in the hotel". They all work!
Hope this helps!