It's easiest to arrive on your own wheels, even though Bahla, the surrounding villages and Nizwa are very much reachable by public transportation. Busses from Muscat (Ruwi) for Ibri and Buriami pass Nizwa and Bahla. Shared taxis from Nizwa are possible (1-2 OR). Several organised tours of the Nizwa area include Bahla, Jebreen and more.
Bahla is small, and the places of interest and main communications are just around the fort.
Wander around in the souq.
The relaxed souq is across the main road from the fort.
Eat and drink
A very decent Turkish restaurant is on your right after the petrol station when driving from the fort (1-2 km) in the direction of Nizwa and the Bahla roundabout. Amongst that main road but down the hill from the fort a few places can conjure decent indian breakfasts and main meals for 1-2 OR per person.
Around Bahla (plan for a few hours walk) and about half way to al-Hamra (left side of the road behind the mountains) there are a few relatively deserted places to pitch your own tent. The Jibreen Hotel and the Bahla Hotel Apartments offer basic accomodation in town. Most visitors choose to stay in Nizwa.
The bus station is just by the fort. Time-tables include a 10:55 bus for Ibri, the ONTC Salalah-to-Dubai-bus (around 2 am, call ahead to make sure the bus will stop), and a few busses for Nizwa. Taxis leave when full (or when you pay too much) for Nizwa, Al-Hamra (1 OR), and Ibri (2-3 OR).
Close-by (10km) Jibreen has a spectacular fort, which like Bahla's is one of the finest in the country. In the village of Al-Hamra (a further 10km or 20km from Bahla) The abandoned parts of the village offer a spectacular and spooky bit of urban exploration. An excellent museum housed in one of the old houses of Al-Hamra makes the journey worthwhile in itself. From al-Hamra a 6km road up to Misfat with its views over the plain, lovely Misfat-House restaurant (book ahead) and irrigated gardens make for a regional highlight.