Upvote:3
If you have time, it's possible to travel by road. It's easy to travel around much of Central Asia on marshrutkas. For example, there are multiple marshrutka between Bishkek and Almaty leaving every hour of the day, taking around 4 hours.
It's a bit complicated getting to Dushanbe from Bishkek by road. The standard traveller route is Bishkek to Osh and then Osh to Dushanbe via the Pamir Highway. Bishkek to Osh is a very long drive, but there are interesting places along the way such as Toktogul, Sary-Chelek and Arslanbob. The Pamir Highway from Osh to Dushanbe takes a few days but is very scenic. Public transport on the highway is very limited, so you might want to get a driver and split costs with others. A faster route overland from Bishkek to Dushanbe goes via Shymkent and Tashkent, but you miss out on much mountain scenery this way.
By the way, the capital of Kazakhstan is Astana, not Almaty. There are several trains a day connecting the two cities, taking around 20 hours.