The application isn't what's suspicious; it's the fact you want 90 days in the US and then are coming back. I don't think either the VWP or the B2 will help you much in terms of getting rid of any suspicion. And the re-entry, as long as it's not from Canada or Mexico, will entitle another 90 days on the VWP. Unless they think you're gaming the system, in which case they can deny you entry and make you get a visa. But then again, if you get a B2 beforehand, and they think you've immigranted to the US, they can deny you entry as well. I might go for the B2, though, just for peace of mind. I think it boosts your story that you knew you were going to visit other countries. But it kind of depends how long you'll be in Central America. If it's just a couple of days, that's going to raise some eyebrows.

https://help.cbp.gov/app/answers/det.../194/related/1

https://help.cbp.gov/app/answers/det.../751/related/1


You might get questioned a bit no matter which route you take-VWP or B2, but the US gets relatively few immigrants-legal and illegal- from Western Europe- so that should help. I'd bring proof of your flights, including your flight back to Ireland. but I wouldn't worry too much.

Have fun in the US!