Is there another option to Corvo? Yes there is, and it's not rocket science. Just 15 miles away is the much larger island of Flores, the accommodation is bountiful, the list of rarities found to date isn't too shabby (e.g. this autumn Upland Sandpiper, Magnolia Warbler, Scarlet Tanager, Savannah Sparrow, White-crowned Sparrow, Indigo Bunting, Rose-breasted Grosbeak and Baltimore Oriole) and, with a bit of organization and amiable weather conditions, day-twitching Corvo is a possibility (day trips to and from have been undertaken by birders on three occasions in the last two years). So far, the number of birders on Flores has been limited, certainly not reaching the density of those on Corvo, however, with a decent number of people looking, there is every possibility that Flores would start to turn up everything its smaller neighbour does.
Autumn birding on the Azores, this year there was literally a kaleidoscope of Nearctic waders in the quarry,... at least through Peter's scope.
Yet to come in this gripping series - The darkside of Corvo: why you might actually prefer somewhere else (seriously).
PS. Getting to the Azores is oh-so-slightly more taxing on the planet than popping to Scilly, if you do decide to go, at least offset your flights (not a perfect solution but the least a travelling birder should be doing nowadays). Companies with carbon offsets approved by the Government Quality Assurance Scheme for Carbon Offsetting include: Carbon Footprint Ltd, Carbon Passport, Clear, PURE the Clean Planet Trust, and Carbon Retirement.