Once they'd reached the restaurant, Severus released Lily's hand in order to get the door for her. Inside, he simply placed his hand on her back, since that was more befitting a man of his age than holding hands, like some maudlin teen. Though he would have been lying if he claimed not to feel that way, during most of the time he and Lily had spent together.
After he'd given his name, the host smiled, pulled out two menus, and a wine list, and gestured toward the dining room, for the two of them to follow, with a cheerful, "This way, Professor Snape." Unfortunately, it was proper etiquette to allow the host to get Lily's chair, and so he did, though he was fairly certain he would get his chance ... eventually.
He took a moment to study the wine list, sure that the sommelier would be over directly. He imagined a lighter red would be called for. Something delicate enough not to overpower a light dish, if that was what Lily wanted, but robust enough to hold its own against something richer. A nice Pinot noir seemed to fit the bill, and they just happened to have an excellent vintage. So, with that settled, he set down the wine list again and looked up at Lily with a smile.