It'll be an awesome trip. Eight sounds like a good number as long as the group dynamics are compatible. Post a TR when you return. I hiked out at Phantom Ranch after 7 days on a 21 day trip.......very hard to leave the trip. Our next shot is two years I hope.
I'm partial to Killer Juice Cabernet Sauvignon. It's a little better than Black Box in My opinion. I'v taken it on a number of raft trips. last time I rowed the Grand I made a flip proof container for 12 bottles of wine out of a 20MM rocket box (old metal ammo can). Put a thin piece of foam (< 0.5inch) in the bottom. Then use the cardboard (0.25 inch version) seperators from a case of wine to space the bottles. If you want put another thin piece of foam or card board on top. I've use this system on the Grand, Cataract, Yampa, San Juan rivers and it works well. If it is hot keep the rocket box in a hatch where it is cool.