There are only two ways to spend the night within the park: camping or in one of the most luxurious lodges on the Circuit. Adventurous campers can choose to overnight with Manyara Bivouac, a mobile camp erected on request, in which you sleep in simple dome tents on stretcher beds and share very basic ablution facilities (www.africatravelresource.com). Those seeking more luxury should inquire about a mobile camping trip with Nomad (www.nomad-tanzania.com), with walk-in tents, comfy mattresses, and en suite bathrooms (short-drop toilet and bucket shower). Both options require group bookings of at least four to eight and are a far cry from overnighting in one of Manyara Tree Lodge's ultrachic forest cabins, where you can dial up your private butler and demand more ice. At around $455 (including all meals, private vehicle and guide, and park fees), the Bivouac camping experience costs the least and is the most authentic, but you can easily guess which of the three options I'd recommend.
Given that camping and the Tree Lodge represent two extremes in the market, most visitors opt for one of the four lodges built along the lip of the escarpment. Given the views -- Lake Manyara shimmering 500m (1,640 ft.) below, dissolving into the Rift floor valley, which stretches all the way to Mount Losimingori -- not to mention cooler temperatures and fewer insects, these escarpment lodgings are no bad consolation prize.
There are also a handful of options available on the lake's northeastern shore (which falls outside the park), of which only Mbunga is worth considering. The cheapest accommodations options are in Mto wa Mbu but are recommended only if you're on a serious cost-saving mission (Mto wa Mbu means "Mosquito Waters" -- spend the night here and you'll see why).
It's also worth nothing that Karatu, gateway to Ngorongoro, lies about 40 minutes from here, so, having traversed the park, there is no reason not to proceed directly to one of guesthouses here, or even direct to the crater rim; best options are discussed under Ngorongoro.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.