Is ReDream the one with the GUI?
I used FlyCast and it .... worked.... One of the emulators crashed on me but I don't recall which one. I'll try ReDream again as it did load but seemed a little goofy but that's probably due to my inexperience with it. Took me a few minutes to realize the mouse was working and had to exit using the commands and not through RetroArch. I'll give it another whirl.
Part of the problem is not really having anything off the top of my head that I would specifically play on Dreamcast. Nearly everything over the years that I had has either aged terribly and not worth the trouble or has been updated or remade on better systems.
PSO has been redone and done better, Skies of Arcadia is on GameCube, etc.