These longer treks are predominately camping treks. Tsum Valley is the easiest and the Manaslu Circuit, both of which can be done as tea-house treks (that is with accommodation provided), is on a similar level to the mid-length Annapurna Circuit, perhaps half a grade more challenging, as are the Upper and Lower Dolpo treks. Then comes the 3 Passes Trek (which can also be done as a tea-house trek). The Makalu and Kanchenjunga Base Camp Treks are strenuous treks, which take you across some higher passes.
If you want to upgrade a stage try a trekking peak.