Buses are plentiful in the entire Saguenay area. There is also a tourist shuttle that runs during summer months, that info can be found on the STS (Societe de Transport du Saguenay) website.
The entire Saguenay region is definitely a must-see. If you have a love for the simple life, this region will be on your mind long after your first visit. Locals don't identify at all with "Saguenay". They identify with the respective pre-merger city (Chicoutimi, Jonquiere, etc...)
Tour the Saguenay Fjord. But while interesting tours are available from Chicoutimi, it may be better to start your tour in Tadoussac, as the fjord is some ways down the river from Chicoutimi and whale-watching is also possible at the confluence of the Saguenay and St. Lawrence at Tadoussac.