I lived in Melbourne for roughly 4 years before leaving last year. Beautiful city, lots of culture and has a more "NA west coast" vibe than Sydney. I lived in the city and it isn't that confusing once you understand that the city was planned from the get-go and is mostly set up as a grid, therefore there are several main roads (Swanston, Elizabeth, Queen, Lonsdale, Burke, Collins) that service the whole city and things generally happen along them. If you love coffee shops, Melbourne is the place to be.. lots of coffee shops where you can sit and do girl watching or just be a hipster.
Taking into consideration that you are into hiking, you could try something different and explore the city on foot. Melbourne is also famous for her laneways which has lots of interesting art and graffiti along the walls.. and not those dodgy back alley crap.. so if you are into that, just explore the city slowly. Unless rules changed, Melbourne has a vibrant busking scene too.. usually lots of buskers on the weekends to entertain you as you explore the city.
There isn't really anything much out in the suburbs unless that is your thing. There is St. Kilda beach that has your regular beach activities and is similar to Bondi Beach in Sydney. Lygon Street near the city has more coffee shops and excellent bars, pubs and italian food. There is also the Queen Vic market with things to see and cheap weird stuff to buy. Southbank is the "new" place to be with crown casino but it's generally meh (other than at the hour every night where they have a fire show beside the river).
If you are looking for a weekend getaway, you can hop on the train from Flinder's station and head to geelong, ballarat or warrnambool where you can hike as those places have nature reserves nearby, wiki those places. For more tourisy stuff, there's philip island or yarra valley. For hiking that is close by to the city, there is dandenong ranges. If you really really dying to hike, there is the grampians about 2-3 hours away from the city.. far but I guess you can get tour buses to get you there if you don't wanna rent a car.
Hope this helps!