Warlord do a number of Pacific theatre vehicles - USMC Shermans with wooden armour, M5/8's & softskins plus LVTs & landing craft. Rubicon also do an excellent M5/8, but they don't come with crew, you'd have to get some from elsewhere (CompanyB do some). Sarissa do a nice Higgins boat (WG carry it also).
For the Japanese, again WG carry a reasonable choice (more than half a dozen types), but not so many others out there do (I'm assuming you're going with 1/56). Company B are one of the few & they also have some of the more unusual & cool vehicles, such as the Ho-Ha halftrack - they're worth a look.
Hope that's helpful!