Ableton Live is a tremendously powerful audio/MIDI DAW, whether for stage use or for composing and producing in the studio. One of the most powerful features of this program is its ability to create strings of loops governed by "Follow Actions," which automatically switch from loop to loop.
To use Follow Actions, load several audio or MIDI loops into cells in a track in the Session window. Make sure the loops are right above one another vertically in the track, with no empty cells in-between.
Be sure Detail View is visible at the bottom of the Session window (you can show or hide Detail View using the arrow at the bottom right of the Session window). Click on the loop name. In the Detail view, make sure the small "L" (at the left bottom) is illuminated, and that you can see the Launch parameters.
Near the bottom of the Launch parameters, there is a Follow Action field, which sets how many times the clip will repeat in bars:beats:16ths.
The two menus below allow you to select from any of eight actions: no action, stop, play again, previous, next, first, last, any, and other. This is the Follow Action that will take place after the clip finishes repeating the number of times you specified in the Follow Action field.
Using these menu selections, you can program a string of clips that will play in the order that you desire. For example, first set your top clip to play four times, then select "Next" from the menu. For the second clip, set it to play two times, then select "First" from the menu. The first clip will play four times, then switch to the second, which will play two times, then switch back to the first, and so on.
There's one more parameter to consider: Chance. The bottom fields in the launch parameters set the probability of whether the Follow Action will occur, so you can add some randomness to the process. A Chance setting of 0 means the Follow Action will never occur, while a Chance of 1 means it will always occur. If you set Chance to 10, then the action will occur approximately 1 out of 10 times.
There's a lot more that you can do with Follow Actions, especially when you combine them with multiple clips, envelopes, and warping. See the Live manual for more information on how to use Follow Actions.