Take care when choosing your accommodations in Quepos/Manuel Antonio. There are very few true beachfront hotels in Manuel Antonio, so you won't have much luck finding a hotel where you can walk directly out of your room and onto the beach. In fact, most of the nicer hotels here are 1km (1/2 mile) or so away from the beach, high on the hill overlooking the ocean.
If you're traveling on a rock-bottom budget, you'll get more for your money by staying in Quepos and taking the bus to the beaches at Manuel Antonio every day. The rooms in Quepos might be small, but they're generally cleaner and more appealing than those available in the same price category closer to the park.
Very Expensive -- If you're coming for an extended stay with your family or a large group, look into Escape Villas (tel. 877/533-8988 in the U.S., or 777-5258 in Costa Rica; www.villascostarica.com), which rents a broad selection of very large and luxurious private villas with all the amenities and some of the best views in Manuel Antonio.
Moderate -- The Best Western Kamuk Hotel (tel. 777-0811; www.kamuk.co.cr) is a dependable option right in downtown Quepos; it's popular with sportfishing enthusiasts.
Inexpensive -- The Widemouth Frog (tel. 777-2798; www.widemouthfrog.org) is a hostel-like option in downtown Quepos, which even has its own swimming pool.