The experience requirements for regionals and medivac are similar so just give it a go and see what happens. If you want to be a medivac pilot then you will want to live in the boonies. The city bases are usually very hard to get if not impossible (ie Perth for RFDS Western). Some of the more romantic places you could be sent to as a medivac pilot are, Gove, Katherine, Tennant Creek, Alice Springs, Port Augusta, Mount Isa, Derby, Port Hedland, Meekatharra, Broken Hill, Dubbo, Charlaville, (spell?) etc etc. Eastern section RFDS is in the city but the most of it is in the boonies.
If you want city living then stick with the regionals.