Well I can give you a personal recommendation from experience. The car service my dad uses is called Star Limo, but it is independently run by a guy (very nice). His name is Nasir, and if you want, you can send me a private message and I can give you the contact info for him. However, I'm not sure if he can accommodate seven people. I know he can accommodate six, but I don't know about seven. Have you considered Super Shuttle?
2007 - Majesty of the Seas (Bahamas)
2009 - Enchantment of the Seas (Western Caribbean)
2010 - Freedom of the Seas (Western Caribbean)
2013 - Golden Princess (Alaska, roundtrip from Seattle)