Depends what all you are planning and when you are going. If it's a busy time of year and the lines are long, you might need the whole day for everything, including all the rides, trails, shows, characters, affection section, and all that. If you are just hitting the shows and a couple of rides for the little ones, 5 hours is probably enough.
Just a word of caution, my kids were 3 and 7 when we saw "It's Tough to be a Bug," and they HATED it. It's dark and a little scary in there. If you are short on time or if they are easily spooked, I'd skip it.
Festival of the Lion King is awesome! Safari is always cool. We all enjoyed the Flights of Wonder bird show, especially my little one, she wanted to go back again the next day. Nemo was good, very much like the movie but on stage. If the adults aren't riding the headliners, your only rides will probably be Kilo Safari and TriceraTop Spin and maybe the Wildlife Train. I'm sure they will want to explore the Boneyard too. Camp Mickie/Minnie is great for seeing the characters! We've actually never made it to Camp M/M, we do a lot of character meals, so we don't usually visit them during park time, but I've seen other peoples' pictures. We've never done the Wildlife Train or the Affection/Conservation Section/Stations, the Discovery Club, Oasis Exhibits, or the trails. There's just always something else we'd rather do on our Disney-time, I'm sure we are missing out, but you just can't see and do it all on every trip!
Hope that helps, have fun!