OPTION I
Day 01:Gangtok to Lachung.

Day 02:Lachung to Yumthang -Drive Back Lachung stay on.

Day 03: Lachung Drive to Lachen. stay on.

Day 04: Lachen drive to Chopta Valley, Thangu later drive   back to Lachen. stay on.

Day 05: Lachen drive back to Gangtok.

OPTION II
Day 01 :Drive from Gangtok to Lachen. stay on.

Day 02 : Lachen - Thangu - Chopta Valley later drive to Lachung. stay on.

Day 03 :Lachung drive to Yumthang Valley - drive back to Lachung. stay on.

Day 04:Lachung drive back to gangtok.