What happened Monday opened with a surge of new optimism about U.S. stocks in general, and stocks in hotel and resort operators in particular. As of 11:45 a.m. EDT, shares of mountain skiing specialist Vail Resorts (NYSE: MTN) are climbing 10.8%, hotelier Marriott International (NASDAQ: MAR) is up 13.8%, and casino operator Eldorado Resorts (NASDAQ: ERI) is doing best of all -- gaining 19.5%. So what Let's begin with the big picture. The stock market as a whole is up today, with the S&P 500 index climbing more than 3% in response to positive interim phase 1 data on a vaccine under development by Moderna Inc., which suggests that the drug in question, mRNA-1273, "elicits an immune response of the magnitude caused by natural infection." Image source: Getty Images. In other words, it appears to "work" as a vaccine against the novel coronavirus SARS-CoV-2, which causes COVID-19. mRNA-1273 is proceeding to phase 2 clinical trials with the FDA. In anticipation of a potential COVID-19 vaccine, economies are starting to reopen across America, and the globe, as social distancing restrictions relax and more people are allowed out to shop, travel, and, perhaps, vacation. Now what That sounds like good news for hotel businesses such as Marriott in general. Today, Eldorado also announced that it will resume operations at Isle of Capri Lake Charles, Belle of Baton Rouge, and Eldorado Shreveport at noon local time today. Eldorado noted that the Louisiana Gaming Control Board is permitting the reopenings so long as the casino operator cuts its "gaming positions" by 50%, and limits foot traffic to no more than 25% of the building capacity. This is a slow start -- but at least a start -- to reopening Eldorado Resorts. Will it be enough to get Eldorado's earnings moving higher again? Perhaps not, or at least not initially, but it should at least give investors a chance to start making back some of the greater than 50% losses the stock has suffered over the past year. Meanwhile, Vail investors just received word that the company will be releasing fiscal third-quarter 2020 earnings numbers on June 4, 2020. The news probably won't be great -- analysts are forecasting a 32% decline in quarterly earnings. But if Vail takes the right kind of optimistic tone in its release -- and if the trend between now and then is toward more businesses reopening, and coronavirus infections continuing to fall, then there's every possibility that no matter what numbers Vail reports, the stock will do well as investor enthusiasm builds. 10 stocks we like better than Marriott InternationalWhen investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* David and Tom just revealed what they believe are the ten best stocks for investors to buy right now... and Marriott International wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of April 16, 2020 Rich Smith has no position in any of the stocks mentioned. The Motley Fool recommends Marriott International and Vail Resorts. The Motley Fool has a disclosure policy.Source