Tough bird to ID. Could be an Eastern Phoebe. The Willow Flycatcher has a long broad bill, rather long wingtips, and a weak eye-ring, according to Sibley, so for now that is my guess. A local bird expert widely known as TOE wrote: the bird in your first photo is an Eastern Wood Pewee. The long primary projections, grayish flanks, overall grayish color, and rather unpronounced white wingbars are all very noticeably Pewee. A Willow will be more greenish/ brown in color, will have shorter primary projections, though not as short as a Least, will not have the extensive gray on the flanks and chest, and the wingbars will be more pronounced and buffy. Also, although not always true, Pewees tend to perch out in the open as this one is doing very often, while the Willows and other empids will stay deeper in the brush, but again, this is not always the case. Congrats on a great trip.
{Northern migrant}. Very difficult to differentiate from the [Western Wood Pewee] when ranges overlap. Usually perched out in the open, sometimes in the canopy and sometimes less than a meter above ground. May allow a close approach.
Africa (entire continent rather than south of Sahara)
AN
Antarctica
AO
Atlantic Ocean
AU
Australasia (Wallacea (Indonesian islands east of Wallace's line), New Guinea and its islands, Australia, New Zealand and its subantarctic islands, the Solomons, New Caledonia, and Vanuatu)
PAL
Eurasia (Europe, Asia from the Middle East through central Asia north of the Himalayas, Siberia and northern China to Japan)
IO
Indian Ocean
LA
Latin America (Middle and South America)
MA
Middle America (Mexico through Panama)
NA
North America (includes the Caribbean)
NO
Northern oceans
OR
Oriental Region (South Asia from Pakistan to Taiwan, plus Southeast Asia, the Philippines, and Greater Sundas)