I also prefer the random orbital sander and have not used my oscillating sander in years. That being said, finish is so much more than just sanding. You have not mentioned what type of wood your project is made from. Softer woods tend to tear and create very small fibers that microscopically protrude above the wood surface. Sanding will not remove all of these and scraping as a final step may be required to remove these fibers. Stain choice is also a factor. Water based stains will raise the grain of the wood. I prefer oil based stains for that reason. You also did not mention what finish you plan to use. Polyurethane does not require the wood be as smooth as say an oil finish might. For poly, I tend to sand to 220 grit, apply 3 coats of finish with a very light hand sanding with 400 grit between coats one and two and then use 000 steel wool with a furniture grade lemon oil on the final coat to remove any final dust particles and give it a nice polish.
For oil finish, search for the the Jarrah box project posted by Harrysin (Harry Sinclair) on this forum. He sanded his box to 1200 grit before applying 5 coats of Danish Oil and his project looks awesome.