[X] Cinnabar Island (Via Plane) - Home of Blaine's secretive fire-type gym, traveling via airplane will be quick but will mean missing out on some adventure.
[X] Fuchsia City (Bike) - Home to the Safari Zone where Willow wishes to catch a Tauros you'd have to carry her on the back of your own bike due to only having one of them with you. It'll be somewhat awkward, but the bike path would allow you to arrive somewhat quickly.
[X] Cinnabar Island (Via Boat) - Taking a longer route of traveling to Pallet Town and hiring a small boat will take notably longer, but it could result in some interesting adventure.