Sorry if this sounds a bit glib but it all depends on the hotel! My experience would suggest that you are unlikely to be sat with others, but if you needed to you could say

Mi dispiace, ma vorrei un tavolo solo per mi e mi moglie. Grazie mille.

(mee dee-spee-ah-chay, ma vorr-ay oon tah-volo solo pair mee ay mee moll-ee-ay. Gra-ts-ee-ay mee-lay.)

I'm sorry but I would like a table for me and my wife only. Thank you very much.