Location Downtown of course. A 5 minute drive to most of the beaches
Prices Downtown has most of the stores, including the central market, the bus station, and several of the hotels, guesthouses, bars and restaurants in Sihanoukville. Bakeries, and most of the banks and medical services. There's even the first ATM machine in Cambodia at ANZ Bank.
You can walk around downtown in an hour or so, and maybe an extra half hour at the Central Market. If you're just getting into town by road, and are looking for a place to stay, you should probably walk downhill from the bus/taxi station and stop in one of the foreign owned restaurants for a drink and advice. The Sihanoukville Advertiser, distributed free almost everywhere, has the latest on prices and services for many hotels.
Also, all the buses to Kampot, Phnom Penh, Kep and Koh Kong leave from the downtown bus station. Find the schedules here.