On your own: One comes to Tanzania primarily for game viewing, with 14% of the country devoted to reserves. This is done on morning and evening game runs in vans or smaller, four-wheel-drive vehicles, usually with a certified driver and perhaps a guide.
There is a definite etiquette involved: A driver never blocks another van's view of the animals, quiet is maintained at all times and nobody ever leaves the van when animals are in sight. Breaking the last rule can be dangerous, because most animals generally ignore the vans until a door is opened or somebody steps out. Then you could be in big trouble.
During our two-day stay in the Serengeti we were fortunate in seeing innumerable lions--one group of 15 polishing off the remains of an enormous cape buffalo 18 feet from our van--the elusive leopard, hordes of wildebeest and zebras, elephants and giraffes, and baboons, the leopard's favorite meal.
Going on safari: They come in all shapes and sizes, from first-cabin affairs to under-canvas outings at camping sites. Three safari operators with a variety of choices: Abercrombie & Kent, (800) 323-7308, recently planned and guided Prince Charles' Serengeti sojourn and also has a fine selection of Kenya and/or Tanzania safaris; Sue's Safaris, (213) 541-2011, has an excellent mix of choices, and Born Free Safaris, (800) 472-3274, specializes in tenting. All will send you brochures with prices.