The Lake District is glorious from spring to autumn, and Bariloche itself is very busy in January and February. Trekking is best from January, as the higher paths may still have snow on them until then, and is generally fine until the end of March. You'll find fewer tourists in March and April.
From Bariloche, hire a car to access more remote places and to make the most of the landscapes. See our car rental recommendations.
Alternatively, many places can be reached by bus; Via Bariloche connects main towns, and within Bariloche there are frequent buses along the lakeshore to Llao Llao, and up to Cerro Catedral for starting hikes and going skiing. Cyclists can hire bikes - though be aware that the terrain is rough.