Optimism from across the Atlantic was evident during the opening day of the fair, as UK publishers fret over the effect of digital on physical sales.
Agent Luigi Bonomi said the more advanced e-book market in the US was making American publishers more decisive than their UK counterparts.
Bonomi said: "It's buzzy and there's lots of excitement. The Americans are hungry for books, I'm not sensing gloom and despair.
"But from the British, there is anxiety about e-books and [print sales] figures being down. A lot of the Americans are telling me that 50% of their authors' frontlist sales are digital. In the UK there seems to be confusion over what the percentage is and what isn't clear is at what level digital is cannibalising print sales."
Penguin Press publishing director Simon Winder, while backing the content on offer this year, echoed Bonomi's feeling about format causing uncertainty: "The show seems really chirpy with lots of great ideas. Overall, I am anxious about format but happy about content."
Elsewhere, publishers noted a busier fair, with the higher headcount than last year evident in areas such as the International Rights Centre. Penguin UK c.e.o. Tom Weldon said the atmosphere was "vibrant and lively", and indicated it was the strongest for at least three years.
Orion c.e.o. Peter Roche said: "It's buzzy, positive, so far, so good."
Mantle publisher Maria Rejt at Pan Macmillan added: "People are splashing the cash."