I believe Chef Mickey's is the only place you'll find all four characters that you listed, and if I'm not mistaken Minnie isn't always there.
Cape May at the BC sounds like it would be a good choice for your group; it's more laid-back than some of the other character meals, and lots of fun with the characters in their beach attire. You won't find Mickey there though. It's Goofy, Chip & Dale, and usually Minnie, although I think I've read reports of times that Minnie wasn't there.
Liberty Tree Taven in the MK is another fun, more laid-back character meal, and it's the one place you're sure to find Minnie as well as Goofy. But Mickey isn't there, and I don't believe Pluto is either.
'Ohana sounds like fun character meal, and like the others I've just listed, doesn't get the throngs of younger children that you'll find at Chef Mickey's and Crystal Palace. However, you also won't see Minnie.
I hope this information helps you decide on a character meal. Whichever one you choose, I'm sure you will all have a great time!
Happy planning.