Yes, SW, a day - even a Saturday - should be enough for BG. As pointed out, Rhino Rally is the hot new ticket and is best done early on (the animals are also at their liveliest then), while the other rides that draw lines (although usually not for a couple of hours after opening) are Gwazi, Kumba, Congo River Rapids, Montu and Tanganyika Tidal Wave. Don't miss the World Rhythms on Ice show at all costs (try to arrive 10-15 minutes early) while the other new shows Moroccan Roll (an amusing pop pastiche) and Jungle Fantasy (acrobats and jugglers) are also worth seeing. With the rides and shows (there is also the Dolphin Show, Bird Show and International Celebration) there is a lot to fit in to the day, and I'm pretty sure you will need all the time available to ensure you do it all justice. Have fun!