Our venue is very spacious so coziness is a challenge. There are three levels - lobby with coat check and the bridal/ketubah room on the first floor, main hall for the ceremony and reception and hall for the cocktail hour on the second floor, and balconies in the main hall.
People who've attended weddings in the space have commented that the guests tend to spread out giving a sense that multiple parties are going on. We're planning on alleviating this partially by closing Balder Hall upon completion of the cocktail hour.
We'd also like to make the spaces more inviting (something along the lines of Krysta's comfy den in the upper right corner of the image below). We're thinking of adding plush throw pillows and bolsters to the fixed straight back chairs.